Hello there ive been having a little trouble with some of the maths behind poker and behind the stats of poker office.

Ok so i have a table that says the chances of hitting a flush draw are:
1.9 to 1 (2 cards to come) and
4.1 to 1 (1 card to come).

So lets say im holding a nut flush draw and sum1 bets the pot giving me 2ish to 1? do i call that with two cards to come or fold based ont he fact that the turn bet will be a pot sized bet also meaning that im not getting the 4:1 i need to call 1 card.

Im just confused about how to "draw" to my hands. Should i be going for 4:1 odds with a flush draw on both streets. Or should i get 2:1 on the flop and 4:1 on the turn?

:@:@

Im hopeless at maths tbh.