Making a hand in Omaha
When you put your hand together in Omaha you always use two of your hole cards and three of the community cards. This makes the board a bit more difficult to read than in a game like Texas Hold'em where you can combine the cards as you wish.
Here are some useful examples that will help you evaluate the strength of your hand in Omaha:
Community cards: Js-8c-3s-4s-Qs.
In Hold'em As would give you the best possible hand. In Omaha you need As-xs to make the nut flush.
Community cards: Ah, 6d, 7c, 8h, 9s.
In this case the nut hand is the same in Omaha and Hold'em - J-T. However, in Hold'em any 10 or 5 would give you a lower straight. In Omaha you would need to be holding 10-9, 6-5 or 5-4 to make a lower straight.
Community cards: Js, Jh, Jc, Jd, 8s.
In Hold'em an Ace would give you the best possible hand - four of kind with the top kicker. In Omaha two Aces will give you the nuts - Jacks full of Aces.
Community cards: Qh, Qs, Qd, Ah, 7c.
In Hold'em the remaining Queen will give you the best hand - four of a kind with an Ace kicker. In Omaha you need to be holding Q-A to make that unbeatable hand.