Ah Omaha, I prefer it to holdem.
Basically its kinda the same as holdem with the exception that you have 4 cards instead of 2.
Now here is where it gets slightly more tricky, you HAVE to use TWO of your four cards and THREE from the board. There is no other way to make your hand, so for example you started with 3 aces in your hand then you can only use two of them and you don't in fact have 3 of a kind.
This means you need to pay attention to the board a bit more as well, if there are 4 cards from one suit then everyone can only still use 3 of those to make a flush.
Then basically the same as holdem the best 5 card hand wins the pot.
In Omaha HiLo 8 or better, things take a turn for being a tad more complex.
In hilo the pot is split between the highest hand and the lowest hand. Again you can still only use 2 of your own cards and 3 from the board. Though now as you are making a high and a low hand, you can use different combinations of the 2 from your hand and the 3 on the board. You don't have to use the same cards for your high and your low. One case where you would want to though is if you had the wheel (A2345) that would give you the best possible low hand and also a straight as your high hand.
Now there is more to making a low hand than you think, the clue being 8s or better. You only have a low hand if you have 5 cards that are less than or including an 8. Straights and flushes are ignored. So the best possible low as I mentioned was A2345 the next best is A2346. Of course this means there needs to be at least 3 cards 8 or lower on the board, if there isn't then no one can possibly have a low hand and the highest hand wins the whole pot.
So assuming 2 people have the high and the low, they then split the pot. If one person has the high and the low hand they win (scoop) the whole pot, which is very profitable. Should one person have the high and 2 people have the same low then the high gets half the pot and the 2 low
hands get a quarter each.
So the aim really is to get the highest and the lowest hand in the same pot to win the whole thing.
Think thats enough for now before I fry yours and my brain. If you want any advice on starting hands and general strategy then just shout and I will follow this up with some more info.