Start from the back if you are machine binding. When you finish on the front you can use a fancy stitch for the last stitch on the front if you want. WHEN you stitch the front be vaaarrry carefull to Pin, Pin, Pin before you start to stitch so the binding looks even when you are done. The reason that you can't go backwards is that the walking foot is not made to go in reverse ( assuming you have a standard walking foot and not a built in one). You can also decrease the stitch size at the beginning and at the end of the stitching to lock your stitches.