let see if i can explain to u all those very important things.
Imagine u hold 9

10

and the board is Q

J

5

the pot has 1000 chips on it.
At the moment u have nothing but a good draw, lets see how many outs do u have to make a winning hand, lets say your opponent has Q

5

.
So u have 8 remaining spades (the 5

will give him a full house) + 3 Kings (we have counted one before the K

) + 3 eights (we counted one before) + running 9s or 10s.
So at the moment u have 14 outs (this situation is one of the bests situations u can face on a holdem hand)
Then theres the 4 and 2 rule. Its very simple, on the flop u multiply the number of outs by 4 and u have the percentage. In this case 14x4 u have 56% chance to make a winning hand.
On the turn u have to multiply the outs by 2 to now what are your chances.
So here if your opponent bets from 0 to 560 chips, u have the odds to call remember 56%.
Theres a more advanded theory that talks about u can call even when u dont have the odds to do it, because if u make your hand the other player is likely to give out all his chips but thats not the case because if a spade comes on the turn or the river he may think his two pair is not that good.
Now lets talk about position. The positions on a 6 handed poker table are the SB, the BB, under the gun, UTG +1, UTG +2 and the button.
On a 9 man table there are three more intermediate positions. The position u are on each moment determine what hands and how u should play them.
For example u shouldnt play something like K

10

, under the gun because if somebody raise from behind u have to fold it, but u can play it from the button if there were no raises before u.
Also u can limp with aces under the gun, trying to induce more action, but it would be terrible if u limp with aces on the button when there were some limpers.
On the internet there are a lot of good tips from experts talking about position and pot odds that would be very interesting to read, i also recommend reading some books as Harrington on holdem 123, supersystem....
I hope u can learn something from everything written here and if u have more questios u can PM me when ever u want