Apply Damage To Player On Collison With Specific Game Object

Yes I do realize this question has been asked many time before. but i have never found one that fits my needs, and yes i am new and i am taking this project 1 step at a time

1. Enemy Object name = enemy

2. player is Main Camera

3. Health Script

   var Health = 100;

   function ApplyDammage (TheDammage : int) { Health -= TheDammage;

     if(Health <= 0)
        {
            Dead();
        }
    }
    
    function Dead()
    {
        Destroy (gameObject);
    }
   
   

4. Raycast Shooting Script

   var Effect : Transform; var TheDammage = 100;

   function Update () {

      var hit : RaycastHit;
        var ray : Ray = Camera.main.ScreenPointToRay(Vector3(Screen.width*0.5, Screen.height*0.5, 0));
        
        if (Input.GetMouseButtonDown(0))
        {
            if (Physics.Raycast (ray, hit, 100))
            {
                var particleClone = Instantiate(Effect, hit.point, Quaternion.LookRotation(hit.normal));
                Destroy(particleClone.gameObject, 2);
                hit.transform.SendMessage("ApplyDammage", TheDammage, SendMessageOptions.DontRequireReceiver);
            }
        }
        
    }
   
   

5. Current attempt that dont work var health = 4; var damage = 1; var wait_time = 2; var lock = 0;

      function OnCollisionEnter(hit: Collision){
        if(hit.gameObject.tag == "enemy" && lock == 0)
                {
                hit.transform.SendMessage("ApplyDammage", 100, SendMessageOptions.DontRequireReceiver);
                }
                }