Added Jan 29, 2008
New York, New Yo...
A caveat: I'm left-handed, so these pictures may be going the opposite direction than you are used to.
Make a knot in the thread, passing the needle through the top folded edge. Running parallel to the fold, pass the needle through the bottom just next to where the thread comes out of the top fold. That is, you want just the tiniest bit of thread to show. So pass the needle under and through the bottom fold, coming back out of the fabric 1/4" away.