I've been reading Sit'n Go Strategy by Collin Moshman and i've got a question about ICM.

Is there anyone out there that can explain this concept in easy to understand language? I know ICM is an important to learn about and I'm completely lost on it.

any help would be appreciated

if you have TPFAP it explains it pretty well. Simply put,

1-your probability of winning a tournament = your stack/total of all stacks
2-your probability of coming in 2d is the sum over all other players of their probability of winning times your stack/all stacks except the presumed winner
3-each finish probability is the sum over all of the possible combinations of players finishing ahead of you times your stack/all stacks except those that finish ahead of you

Then you take the probability of each finish position times the prize for that position and thats your equity with that chip stack.

In a SnG its usually used in push/fold or call/fold situations, and compares your ICM based equity if you fold vs your ICM based equity if you play and win or play and lose, each weighted by the probability of winning and losing. Obviously that last calculation depends on putting villain on hand ranges and calculating your hand equity vs that range. For bubble and in the money situations that can be pretty well optimized. See Sitngo End game tools web site.

Can someone touch on hand equity, how to caluculate and how to use it?

Usually you use a chart or a tool like pokerstove or http://www.propokertools.com/.

The easiest way is to say that the villain will shove the top x% of hands, and compare your hand strength to that range:

Hand Pot equity Wins Ties
KT 36.08% 1,322,875,880 106,848,348
13% 63.92% 2,385,289,084 106,848,348

Then you'd compare your equity with the pot odds.

For calling ranges, the calculation is made by comparing the amount you win from the blinds/antes the % of the time that they fold + the amount that you win the % of the time they call and you win to the amount you lose when you are called and don't win.

After the flop, maybe you can narrow your opponent to a range of actual hands based on the action:

board: Qs9d2h
Hand Pot equity Wins Ties
AcAs 59.44% 21,186 0
22,9T,Q9,KQ 40.56% 14,454 0

If your opponent's range is weighted towards a hand or set of hands, adjust accordingly. Same goes for if there are bluffs in his range.

Usually it isn't really possible to do this while in a hand, but the more you think about hand ranges and run simulations, the more accurate your decisions will be.

Please note that these are not ICM calculations. This is just in response to the question about equity vs. ranges.

Do you have some kind of tool that gives you this instantly or do you think all that while your playing?