To iceskate backwards, start walking backwards as if your are dragging your feet, drag for a little bit then lift your feet and drag again, and then move your feet inwards and outwards like this:
L R ( ) ( ) ( ) ! ! ! ! ) ( ) ) )
Move your right foot first then follow a second or 2 later with your left.
Don't lift your feet unless you wanna start the first bit to gain more speed
Watch this YouTube video to learn more: