How to make my gun shoot down [C#]

So, I have my gun and it can shoot up and and forward, but not down. Its a 3rd person shooter, and the shooting system is click and fire where the courser is. Can someone help me out?

using UnityEngine; using System.Collections;

public class Shoot : MonoBehaviour { [Range (0, 50)] public int Change_Despawn_Bullet; [Range(0, 50)] public int Bullet_Forward_Force; [Range(0, 50)] public int WaitTimeRelaod; [Range(0, 100)] public int ClipSize_Number = 12; [Range(0, 100)] public int AmmoSize_Number = 36;

 public Transform playerTransform;
 public float offset = 90;
 private GameObject tempGameObject;
 public GameObject Bullet;
 public GameObject Bullet_Spawner;

 private Damage_Heal ammo_clip;

 private void Start()
 {
     ammo_clip = GetComponent<Damage_Heal>();

     tempGameObject = new GameObject();
     ammo_clip.UpdateAmmo_ClipBar();
     ammo_clip.AmmoSize = AmmoSize_Number;
     ammo_clip.ClipSize = ClipSize_Number;

     if (playerTransform == null)
     {
         playerTransform = GameObject.FindWithTag("Player").transform;
     }
 }

 public void Update()
 {
     ammo_clip.UpdateAmmo_ClipBar();

     if (Input.GetKeyDown("r"))
     {
         StartCoroutine("Reload_Animation");    
     }

     RaycastHit hit = new RaycastHit();
     Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);

     if ((Physics.Raycast(ray, out hit)) &&
         (Bullet_Spawner != null) &&
         (Bullet != null) &&
         (ammo_clip != null) &&
         (ammo_clip.ClipSize > 0) &&
         (Input.GetButtonDown("Fire1")))
     {
         Gun_Controll(hit);
     }
 }

 IEnumerator Reload_Animation()
 {
     while ((ammo_clip != null) && ammo_clip.ClipSize >= 0 && ammo_clip.ClipSize < 12 && ammo_clip.AmmoSize > 0)
     {
         yield return new WaitForSeconds(WaitTimeRelaod);

         ammo_clip.AmmoSize -= 1;
         ammo_clip.ClipSize += 1;
         ammo_clip.UpdateAmmo_ClipBar();
     }
 }

 public void Gun_Controll(RaycastHit hit)
 {
         tempGameObject.transform.LookAt(hit.point);

         GameObject Temporary_Bullet_Handler;
         Temporary_Bullet_Handler = Instantiate(Bullet, Bullet_Spawner.transform.position, Bullet_Spawner.transform.rotation) as GameObject;
         Temporary_Bullet_Handler.transform.Rotate(Vector3.left * 90);

         Rigidbody Temporary_RigidBody;
         Temporary_RigidBody = Temporary_Bullet_Handler.GetComponent<Rigidbody>();
         Temporary_RigidBody.AddForce(tempGameObject.transform.forward * Bullet_Forward_Force * 100);
         tempGameObject.transform.LookAt(hit.point);
         Destroy(Temporary_Bullet_Handler, Change_Despawn_Bullet);

         ammo_clip.ClipSize -= 1;
         ammo_clip.UpdateAmmo_ClipBar();

     }
 }