Swing the free leg around slowly and shift your hips at the same time. Let your foot rock up towards your toe, and swing it backwards at the same time as your leg and hips go. You should now be skating backwards on one foot. This requires you to be on only two wheels. You can do it on your heels, on your toes, or the easiest on one toe and one heel.
Most people feel comfortable spinning counter-clockwise.
This is the common direction to spin in figure skating unless you are left-handed and do everything in the opposite direction. I will explain a right handed, toe-heel two foot spin like would be done on ice. You will be on the toe of your left foot and the heel of your right and will spin counter-clockwise. Start with your arms out to your side and feet slightly apart. 90degrees in the clockwise direction.