How can I weld models or parts to the camera? [FPS]

I'm trying to make a fps like the famous Phantom forces not exactly but you get the idea. The problem is I really don't know where to start I can't even make welds I don't know what to do and I am learning CFame:lerp() luckily but I don't know how to weld a model to the camera. An example would be extremely helpful ! oh and I can do some camera manipulation like I can move the camera to lerp to another and I can do that stuff.