(HELP WANTED)

What my problem is I made a bullet shooting system and I can’t figure out how to make the bullet go in one direction instead of going straight down, Can you please Help?

This is my code

using UnityEngine;

public class Gun : MonoBehaviour
{
public float damage = 10f;
public float range = 100f;
public float fireRate = 15f;
public float impactForce = 30f;

public Camera MainCamera;
public ParticleSystem GunShot;
public GameObject impactEffect;
private float nextTimeToFire = 0f;

// Update is called once per frame
void Update()
{

if (Input.GetMouseButtonDown(0) && Time.time >= nextTimeToFire)
{
nextTimeToFire = Time.time + 1f / fireRate;
Shoot();
}
}

void Shoot()
{
GunShot.Play();

RaycastHit hit;
if (Physics.Raycast(MainCamera.transform.position, MainCamera.transform.forward, out hit, range))
{
Debug.Log(hit.transform.name);

Target target = hit.transform.GetComponent();

if (target != null) ;
{
target.TakeDamage(damage);
}

if (hit.rigidbody != null)
{
hit.rigidbody.AddForce(-hit.normal * impactForce);
}

GameObject impactGO = Instantiate(impactEffect, hit.point, Quaternion.LookRotation(hit.normal));
Destroy(impactGO, 2f);
}

}
}

This is my shooting code

using UnityEngine;

public class Shooting : MonoBehaviour
{
public GameObject bullet;
public float speed = 100f;

// Update is called once per frame
void Update()
{
if (Input.GetMouseButtonDown(0))
{
GameObject instBullet = Instantiate(bullet,transform.position,Quaternion.identity) as GameObject;
Rigidbody instBulletRigidbody = instBullet.GetComponent();
instBulletRigidbody.AddForce(Vector3.forward * speed);
}
}
}

‘Shorthand for writing Vector3(0, 0, 1)’
Vector3(x,y,z)