There are five colours actually: red, blue, black, white and green. So yeah, just like Duel Masters. Duel Masters is pretty much just a simplified version of MtG.
I'll try to sum it up, but I'll fail, I guarantee.
You have land, and each card other than basic land has a land cost to be played.
[img139]http://www.groundzerocomics.com/images/MTGgameday_reya.jpg[/img139]
So for this card, if you look at the top right corner of the card, you have symbols. There are three white symbols, meaning you have to tap three plains land, and there is also a number '6' in a circle. The number in that circle means that you have to tap six (in this case) land of any colour in addition to those three plains in order to play this creature. Same goes for enchantments, instants, artifacts and the like.
Now, turn your attention to the two numbers, 4/6, in the bottom right corner. This is the creature's power and toughness, and you can pretty much think of this as a creature's attack and defense, to related to Yu-Gi-Oh. When this creature attacks a player or creature, it will deal four damage and be able to withstand six damage in return. So, say your opponent blocks your attack with a 2/4 creature, your four power is enough to kill the opponent's creature, but your opponent's creature's two power is not enough to kill your creature as your creature's toughness is greater than the other creature's power. There are instants and enchantments that increase/decrease power and toughness too, and these are factored in. Creatures are tapped when they attack (unless they have the keyword Vigilance), and this means they cannot block during your opponent's turn. Also, creatures cannot attack on the turn they are summoned because of summoning sickness (unless the creature has Haste.
Cards other than creatures and land are simple enough, you play them and do what the card says. The type of card is the only real difference here. Enchantments, artifacts and sorcery cards can only be played during your turn, whilst instants can be played at any time. Instants last until the end of the current turn, enchantments stay on whatever they enchant until they are destroyed/whatever they are enchanting is destroyed, sorcery cards just last until the end of your turn unless their effect flows over to another turn, but the card is still put into the graveyard straight away. Artifacts have abilities, and they can be activated as though they were instants (unless they state otherwise, but generally this is the case).
Uh.. each player starts with 20 life, and attacks to a player subtract the attacking creature's power from the targeted player's life.
Confusing probably, I know. Ask me to clarify anything if you want.