GUI SpaceShip Movement Problem!!! Please help!!

using UnityEngine;
using System.Collections;

public class simpleMovement : MonoBehaviour 

{
	public float speed = 0.00f;
	public float rotSpeed = 10.0f;
	public float strafeSpeed =10.0f;
	private float engineSpeed = 0.0f;
	public float pitchConstant = 1.0f;
	public float yawConstant = 0.0f;
	public GameObject boostersprefab;
	public GameObject boosterPos;
		
	private GameObject instantiated;
    private bool instanBoostersExist;		
	
	// GUI texture
	
	public GUITexture forwardPitchButton;
	public GUITexture backwardPitchButton;
	public GUITexture leftPitchButton;
	public GUITexture rightPitchButton;		
	
	
	
	
	// Booster Start Function
	void boostersStart()		
	{  
        if(instanBoostersExist == false)	
		
		{			
		  instantiated = (GameObject)Instantiate(boostersprefab, boosterPos.transform.position, boosterPos.transform.rotation);
		  instantiated.transform.parent	= boosterPos.transform;
		  instanBoostersExist = true;			
		}		
	}		
	
	// Booster Stop Function
	void boosterStop()
	{		
	    if (instanBoostersExist == true)
		{		
			Destroy(instantiated,0.2f);
		    instanBoostersExist = false;
		}	
	}
	
		
	
	void Update()
		
	{		
	// Axis Declaration	
	float pitch = Input.GetAxis("Pitch")*pitchConstant; 		
	float yaw   = Input.GetAxis  ("Yaw")*yawConstant;		
	float roll =  Input.GetAxis ("Roll");
	float gas =   Input.GetAxis ("Gas");		
	
		
	Vector3 strafe = new Vector3 (Input.GetAxis("Horizontal")*strafeSpeed*Time.deltaTime,Input.GetAxis("Vertical")*strafeSpeed*Time.deltaTime,0);		
			
		// Engine Mechanism		
		
		 if (engineSpeed <10 && engineSpeed > -3)
		 {
		  engineSpeed += gas;			
		  boostersStart();		  
		 }
		
		 if(engineSpeed > 10)
		 {
		  engineSpeed = (9.99f);	
		 }
		
		 if (engineSpeed<-3)
		 {
		  engineSpeed = (-2.99f);		
		 }
		
	      else if(Input.GetKey("z"))// Brake
		 {
		  engineSpeed = (0.00f);
		  boosterStop();		  
		 }	
	
	 
		
		
		
		
	// SpaceShip Physics Movement
		
	rigidbody.AddRelativeTorque(pitch*rotSpeed*Time.deltaTime,yaw*rotSpeed*Time.deltaTime,roll*rotSpeed*Time.deltaTime);
	
	rigidbody.AddRelativeForce(0,0,engineSpeed*speed*Time.deltaTime);	
		
	rigidbody.AddRelativeForce(strafe);	
		
		
	}	
}

How do I use the GUI button press (already I have tried some ways, but am not able to achieve the effect) which is been assigned with respective texture to move the ship in yaw and pitch position. I have found the way to achieve this using keyboard controls, Please some one help me to fix this code for GUI texture. Thanks a lot, If you can please explain a bit, It would be of immense help. Thanks

You created two exact questions from the look of it, answered the other.