its hard to understand like this how about creating a video tutorial
Hope this helps -- I decided to skip titles and shit and just put the notes in the video description.
from footstall, clamp the ball tightly against your shin and swing leg outwards and then back behind your standing leg. keep the ball clamped and when your ball-leg crosses your standing leg (behind you), FLEX your leg, like doing a hamstring curl, and then release the ball off your toe, creating some spin. simultaneously, do a slight pivot on your standing foot so that your leg can come around to catch the ball to carry on juggling. sorry for the poor video, it was made in haste.
it helps (a lot) if your shin is a bit sweaty to help the ball stick.