Click on the Deck, Cards, Discard, and Exile to pull up their menus. Don't do too many things too fast as to avoid breaking the game. Drag around cards when they're in your Hand or on the Battlefield. [Command Zone counts as your hand] When viewing the Discard, Exile, or the Deck. Click [X] to stop viewing the cards. Remix this to create yer own custom deck! [It might just take a while to make]
Credits : MTG for creating the game in the first place, and the way the cards are set up.