How do i learn how to calculate percentage of my chance to win in a poker hand againt other players?

That's an open ended question, the % changes with every card delt as well as the amount of players and don't forget about the burn pile. Think of it like this say you hold a flush draw and two more of your suited cards show up out of the flop,...still two cards left and there's only four suits,....so you have a 1 in 4 chance x 2 of hitting your card. That's my favorite hand BTW.