So, you already broke the first rule of EDH and played with multiples... You can't play more than one of any non-basic land.
You also have to chose a legendary creature to use as your general.
Honestly, I.. I just don't know where to begin teaching you about the format--So I'll let somebody else do it for me. Bennie Smith has a fantastic article series on Starcitygames.com (and they're all free) about playing commander. He also has a great couple of primers to help you get into the format.
http://www.starcitygames.com/magic/mult
art_1.html
http://www.starcitygames.com/magic/mult
art_2.html
http://www.starcitygames.com/magic/misc
art_3.html
read these three articles before trying to build another deck. He also has some great suggestions for cheap cards to pick up to power your EDH decks. It looks like you're trying to play GW, and that's a fantastic color to start with--there are a lot of good GW EDH cards that have been printed lately.