Mitering is one of those skills that are easy after you do it once. You used to be able to find a friend, neighbor, mother. grandmother, or aunt who could show you quickly, but most of us don't have Sewing Buddies anymore.
Thank goodness for Youtube, it's not as good as a live human being, but will do in a pinch. Sharon Schamber has a great 3 part demo on Youtube for bindings, which includes mitering.