Search online or
poker books to get the relevant poker math information, once you have learnt the basic knowledge you can start applying it to your game.
You can even watch some poker shows like Poker after dark and sit down working out the pot
odds for each hand, doing this in a
online poker game at first can become very daunting as you have a set amount of time to asses the situation do the maths put your opponent on a hand and work out if its a profitable call.
Trust me, it takes some time but the more you do it the easier it becomes, most of it isn't hard maths as we know there are 52 cards in the deck 4 suits of 13 cards, you have 4 to a flush on the flop we are holding 2 cards and there are 3 cards out, there are 9 cards that hit our flush and 38 that dont (flush draw) 38/9= 4.22. Most odds over time will just be general knowledge.
There are also a lot of hand odds charts you can find online to help you get started.
I may have waffled on and been no help at all but I hope you get something out of this.