with hammer ? if so can you tell me exactly how because im not good with hammer

Go to tools->prefab factory->add prefab. Select your prefab. Then in your prefab tool bar thingy push "to World", then go to the catagory that you put your prefab in(you'll want to start your own if you use them), then click insert original prefab and whala.

I completely dislike prefabs...even if it's anything of my own, I'll just copy + paste anyway...and I don't like using others' work (often it isn't up to par) but I guess if you really want you can use prefabs...