Can someone help me with GUI script what I have?

Hi Im using FPS kit by Aiden Studio and I want to add simple thing. If I click on button, player name in GUI will be red. There is script what generate GUI with everything. Please help me!
using UnityEngine;
using System.Collections;

public class characterControls : MonoBehaviour {


    public int health = 100;
    public float speed = 10.0f;
    public float gravity = 10.0f;
    public float maxVelocityChange = 10.0f;
    public bool canJump = true;
    public float jumpHeight = 2.0f;
    private bool grounded = false;

    public SkinnedMeshRenderer[] skinnedPlayerMeshes;
    public MeshRenderer[] playerMeshes;

    public GameObject fpCam;

    public float bloodyScreenDuration = 3;

    public Texture[] bloodyScreens;

    float bloodTimer = 0;

    public PhotonView pv;

    public GameObject ragdoll;


	public GUISkin guiSkin;

    mouseLook mL;

    public bool isPaused = false;

    void Awake()
    {
        GetComponent<Rigidbody>().freezeRotation = true;
        GetComponent<Rigidbody>().useGravity = false;
        if (pv.isMine)
        {
            pv.RPC("setName", PhotonTargets.AllBuffered, PhotonNetwork.playerName);
     
            pv.RPC("updateWep", PhotonTargets.AllBuffered, PhotonNetwork.player.GetScore());
            mL = fpCam.GetComponent<mouseLook>();
		
        }

      
    }

    [PunRPC]
    public void setName(string nm)
    {
        gameObject.name = nm;
    }

    void Update()
    {
        if (bloodTimer > 0)
        {
            bloodTimer -= Time.deltaTime;
        }
    }

    void FixedUpdate()
    {
        if (grounded && pv.isMine)
        {
            // Calculate how fast we should be moving
            Vector3 targetVelocity = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
            targetVelocity = transform.TransformDirection(targetVelocity);
            targetVelocity *= speed;

            // Apply a force that attempts to reach our target velocity
            Vector3 velocity = GetComponent<Rigidbody>().velocity;
            Vector3 velocityChange = (targetVelocity - velocity);
            velocityChange.x = Mathf.Clamp(velocityChange.x, -maxVelocityChange, maxVelocityChange);
            velocityChange.z = Mathf.Clamp(velocityChange.z, -maxVelocityChange, maxVelocityChange);
            velocityChange.y = 0;
            GetComponent<Rigidbody>().AddForce(velocityChange, ForceMode.VelocityChange);

            if (health <= 0)
            {
                pv.RPC("Die", PhotonTargets.AllBuffered, null);
            }

            // Jump
            if (canJump && Input.GetButton("Jump"))
            {
                GetComponent<Rigidbody>().velocity = new Vector3(velocity.x, CalculateJumpVerticalSpeed(), velocity.z);
            }

            isPaused = Input.GetKey(KeyCode.Tab);

            mL.enabled = !isPaused;

            if (isPaused)
            {
                Cursor.lockState = CursorLockMode.None;
                Cursor.visible = true;
            } else
            {
                Cursor.lockState = CursorLockMode.Locked;
                Cursor.visible = false;
            }
            if (Input.GetKeyUp(KeyCode.F5))
            {
                pv.RPC("gotKill", PhotonTargets.AllBuffered, "loser");
            }
        }

        // We apply gravity manually for more tuning control
        GetComponent<Rigidbody>().AddForce(new Vector3(0, -gravity * GetComponent<Rigidbody>().mass, 0));

        grounded = false;
    }

    void OnCollisionStay()
    {
        grounded = true;
    }

    float CalculateJumpVerticalSpeed()
    {
        // From the jump height and gravity we deduce the upwards speed 
        // for the character to reach at the apex.
        return Mathf.Sqrt(2 * jumpHeight * gravity);
    }

    string killerWep = "World";
    string killer = "Null";

    [PunRPC]
    public void ApplyDamage(int dmg, string wepName, string kilr)
    {
        if (kilr != gameObject.name)
        {
            health -= dmg;
            killerWep = wepName;
            killer = kilr;

            if (pv.isMine)
            {
                blood = bloodyScreens[Random.Range(0, bloodyScreens.Length)];
                bloodTimer = bloodyScreenDuration;

                if (health <= 0)
                {
                    pv.RPC("Die", PhotonTargets.AllBuffered, null);
                }
            }
        }
    }

    Texture blood;

    Vector2 scroll = Vector2.zero;

    void OnGUI()
	{
		GUI.skin = guiSkin;
		GUI.Box (new Rect (10, Screen.height - 100, 145, 30), "HP | " + health);
		if (bloodTimer > 0) {
			Color c = Color.white;
			c.a = bloodTimer;
			GUI.color = c;
			GUI.DrawTexture (new Rect (0, 0, Screen.width, Screen.height), blood, ScaleMode.StretchToFill);

		}
		if (isPaused) {
			GUILayout.BeginArea (new Rect (Screen.width / 2 - 500, Screen.height / 2 - 200, 300, 500));
			GUILayout.BeginVertical ("Box");
			GUILayout.Label ("Paused");
			scroll = GUILayout.BeginScrollView (scroll, "Window");
			GUILayout.BeginHorizontal ();
			GUILayout.Label ("Player ");
			GUILayout.Label ("Kills");
			GUILayout.Label (" Weapon");
			GUILayout.EndHorizontal ();
			foreach (PhotonPlayer pl in PhotonNetwork.playerList) {
				GUILayout.BeginHorizontal ("Box");
				GUILayout.Label (pl.NickName + " ");
				GUILayout.Label (pl.GetScore () + " ");
				GUILayout.EndHorizontal ();
			}
			GUILayout.EndScrollView ();
			if (GUILayout.Button ("Suicide")) {
				if (pv.isMine) {
					pv.RPC ("ApplyDamage", PhotonTargets.AllBuffered, 10000, "Suicide", "Self");
				}
			}
			if (GUILayout.Button ("Resume")) {
				isPaused = false;
			}
			if (GUILayout.Button ("Disconnect")) {
				PhotonNetwork.LeaveRoom ();
				UnityEngine.SceneManagement.SceneManager.LoadScene (1);
			}

			GUILayout.EndVertical ();
			GUILayout.EndArea ();
		}
	}

	bool dead = false;

    [PunRPC]
    public void Die()
    {
		if (!dead)

        {
            dead = true;
            Destroy(gameObject);
            if (pv.isMine)
            {
                Cursor.lockState = CursorLockMode.None;
                Cursor.visible = true;
                PhotonNetwork.Instantiate(ragdoll.name, transform.position, transform.rotation, 0);
                GameObject.Find("_Room").GetComponent<roomManager>().isSpawned = false;
				GameObject.Find("_Room (2)").GetComponent<roomManager>().isSpawned = false;

				GameObject.Find("_Network").GetComponent<PhotonView>().RPC("getKillFeed", PhotonTargets.All, PhotonNetwork.player.NickName, killer, killerWep);
                if (GameObject.Find(killer) != null)
                {
                    GameObject.Find(killer).GetComponent<PhotonView>().RPC("gotKill", PhotonTargets.AllBuffered, PhotonNetwork.playerName);
                }
            }
        }
    }

    [PunRPC]
    public void gotKill(string victim)
    {
        if (pv.isMine)
        {
            PhotonNetwork.player.AddScore(1);
            pv.RPC("updateWep", PhotonTargets.AllBuffered, PhotonNetwork.player.GetScore());
        }
        Debug.Log("Killed " + victim + "! Score: " + PhotonNetwork.player.GetScore());
        
    }

    [PunRPC]
    public void destroy()
    {
        Destroy(gameObject);
    }
}

@juraj123 Hello there, you just need to make the same thing you do to change the color from the GUI, something like this:

if (damage == true) { GUI.color = Color.red; } //This only happens if there's a damage.

EditorGuilayout.Label ("Your Content");

if (damage == true) { GUI.color = Color.white; } //This only happens if there's a damage.

This is just an example, but this is the way to do what you want, hopes this helps, cheers.