This is almost impossible to do via a forum post. Too many factors. But assuming you address the ball and grip your club properly, try this exersice that will likely having you drawing or hooking the ball, but you will be able to feel the difference from what is causing your slice and adjust accordingly:
With a strong grip (left hand rotated clockwise on the grip allowing you to see all four knuckles), keep your right elbow loosely tucked in to your right side during your backswing and keep it there on your downswing, forcing an inside out, rounder swing plane around your spine. On the downswing, with right elbow tucked, focus only on the three little fingers of your left hand coming staight down onto the ball...the clubhead will naturally release and the ball should go left.
Give it a try....