I guess i have the advantage of not having played other futbol sims so I had no preconceived notions, so I read the official help (sparse as it is) and the tutorials and tips. You have nothing to be ashamed of.
re defense, http://forum.topeleven.com/tutorials...-part-1-a.html
That's the bible I follow for T11. So if a player covers his square and all adjacent squares, it follows, and experience bears out, that they cover adjacent squares less effectively and with less priority than their own. (when using zonal D)
I literally NEVER use a 4 wide D, because I'm always able to exploit it on attack. I use 3 central defenders, or 3n + a DMC (because the DMC, in addition to strengthening the middle, also adds to midfield possession numbers). If I really feel i need to cover the flanks i go 5 wide, or 4 wide WITH a blue arrowed DMC.