How can I make my own Chams?

I'm super noobish when it comes to computer modding, but xbox 360 modding I can do lol. I have downloaded 2 different .dll's for PB and I have used the MPGH injector on both of them and it still doesn't work. I'm thinking that maybe if i make my own Cham, it might help. Or maybe I am just doing something wrong. Somebody, anybody, wanna help me out here?