can someone help me, its so confusing 
On the left you have the list of cards you own, in the middle, the big green space you have your deck. You use the deck in card battles, and to make one you select the desired cards by clicking them. On the right, you will have a card's description once you do click on it. You can also click that orange "!" on the right corner, iirc it gives some info about the system, and if you still don't get it, save your game, start a new one, pay attention to the tutorial this time and load this save back again.Or you can just use common sense...