How to calculate odds

[ATM]

Ive been reading Theory of Poker and found it extremely helpful but im still having trouble with odds. a few times during the book sklanksy refers to things like if you are drawing to your flush you are 5 to 1 against etc how do i know or figure out that i am a 5 to 1 against and then once i know that do i compare that to the size of the pot and if the pot is bigger than my odds is it the right call. Im not to sure about this stuff just now and wondering if anyone will help me out and explain it in laymans terms