There are probably very few players out there who know and understand all of the gaming concepts. There are so many details worked into it in some way or other that even experienced gamers like me keep on discovering new things. The game tries to model small scale modern warfare as realistic as it can get it. Modern warfare is extremely complicated so the game by default will be complicated too. That doesn't mean you need to know a lot of things to play and enjoy the game.
As baggypants suggested, small scale units may be a good starting point. Another suggestion is to start with the earliest years (40's or 50's) as the equipment is less complicated and the units less lethal (and mistakes wouldn't be as deadly as in current era combat).
Final suggestion, find someone (experienced) to play a simple PBEM set-up with. Ask relevant questions as you go along the game and also get him to explain why/how he does certain things the way he does. You'll soon get the hang of it. Besides this forum you might also want to try the Blitz wargaming club for a PBEM 'mentor' (at
www.theblitz.org).
Narwan