Help using addresses?

Okay, so im making a Mw3 Survival mode trainer... My question is: imagine like 00545645<---my ammo address and it holds value of 30?<--- my ammo, how can i "freeze" it with WriteProcessMemory? Any help? :P

-Thanks

"Freezing" a value is actually a misleading term. Game cheat tools that support this feature actually just repeatedly write to the address at a certain interval. The other option you have is to simply find out what writes to that address and either destroy functionality (remove the decrementing write) or change functionality (set the value).

Just use cheat engine and you're done, or WPE pro. Those are my two favorite Memory Cheats.
Also, if you want to make a marvelous Trainer put all that into VB, and make a sexy D3D.