Put your front foot behind your front truck's bolts. You want this foot at an angle. It's going to be pretty far back on the board, but that's OK.
Your back foot is placed so that the ball of your foot is nestled in comfortably in the little dip right before your tail goes up, on the toe-edge side of the board. I like to have my toes hang over, but if it works better for you to not, then don't!
Practice being comfortable with shifting your feet to this position while rolling. Once you are good to go, you can try the 360 flip!