how do i give my first person a gun

ok i'm in need of some help or a lot of help i need to know how to give a 1st person view a gun and know how shoot???????????? it plz help

The FPS tutorial can explain this better than I FPS Tutorial, but the basic idea is fairly simple to implement. First you make the camera a parent of your gun. Then you position the gun in the spot you want on the camera, slightly ofset down and forward. That's how to position the gun.

To fire the gun, you have to write a script that the FPS tutorial explains quite well. Basically, you say something like this to shoot something with bullets that the player would not normally be able to see like machine gun fire or small rounds.

var ray = Camera.main.ScreenPointToRay(Input.mousePosition);

var damage  = 15;

var hit : RaycastHit;

if(Input.GetButton/*Down*/("Fire1")) {
     if(Physics.Raycast(ray, hit, Mathf.Infinity)) {
          hit.transform.BroadcastMessage("ApplyDamage", damage, SendMessageOptions.DontRequireReciever);
     }
}

If you want you shoot larger projectiles, you should probably use rigidBodies. And again the FPS tutorial is a good reference.