C++ Memory write/read functions?

I tried googling but it didn't work out, so I'm asking this here.


I'm trying to make a CS:S hack, a simple sv_cheats bypass. All i need is to connect to the process, and edit a memory adress and "freeze it".
Then I need a hotkey function to make it listen to the F12 key and then activate the sv_cheats bypass.

Does anyone here know how to make something like this?

I know the adress.