Right so here is the thing, first of all you need to understand what the code is your trying to compile and what it exactly does through the process of injecting into crossfire.exe, Using source codes off this site you don't need any sort of C++ Knowledge unless they have leech protection on them, with leech protect it most probably wont be the most hardest thing ever to know to put back in so you will just need to know the basics and just to say if your using source code/snippets then remember to just give credits to the users you got the code off. Oh and one thing you need to know is how to compile the code to make your dll to inject into crossfire.
Hope this was a little more helpful to you.