You should read the stickied threads and use the Search features, if for no other reason than to find out as to whether or not this series of questions has been asked before.
The stuck threads are there for the specific purpose of answering common or frequently-asked questions, and to denote any specific rules pertaining to the subforum in which they are posted. You'll find them in every subfroum.
The Search features will allow you to seek out and find existing threads, in which you may, of course, participate....but reading first is strongly encouraged.
Specifically, Royal has the right of it, so maybe this'd be a good place to start: http://www.m4carbine.net/showthread.php?t=28658