Set a delay for firing

Current I'm trying to rework someones template as a project for a game. Current the fire rate of the guns is basically as fast as you can hit the fire button. After looking into it I think I can set a delay? Please help I'm quite the noob when it comes to coding

the current code for weapon behaviour:

public class weaponBehaviour : usableObjectScript {

 [Tooltip("ammo prefab")] public GameObject ammo;
 [Tooltip("number of ammo")] public int ammoNumber;
 [Tooltip("shoot power")] public float shootPower;
 [Tooltip("animator state")] public int fightState;

 [HideInInspector] public List<GameObject> ammunition; // list of an ammo

 // Use this for initialization
 void Start () {
     
     prepareAmmo ();
     prepareObject ();
     StartCoroutine ("bulletdellay");
 }
 
 // Update is called once per frame
 void FixedUpdate () {

 }


 void prepareAmmo() 
 {
     ammunition = new List<GameObject>(); // creates ammo list
     for (int i = 0; i < ammoNumber - 1; i++) 
     {
         GameObject newAmmo = Instantiate(ammo, Vector3.zero, Quaternion.identity) as GameObject; // creates new ammo
         ammunition.Add(newAmmo); // puts new ammo in array
         newAmmo.SetActive(false); // disables ammo

     
     }
 }



 public override void checkFighter (GameObject fighter) // checks for fighter
 {
     if (fighter.gameObject.layer == 8 || fighter.gameObject.layer == 9) 
     {
         fighter.gameObject.GetComponent<fighterScript>().use(gameObject); // fighter takes weapon
         gameObject.SetActive (false); // disable gameObject
     }
 }
     
 public class ExampleClass : MonoBehaviour {
     public Transform bulletPrefab;
     void Start() {
         Transform bullet = Instantiate(bulletPrefab) as Transform;
         Physics2D.IgnoreCollision(bullet.GetComponent<Collider2D>(), GetComponent<Collider2D>());
     }
 }

}