When you're out in the water, your feet and your hands are your only method of propulsion, so to catch a wave, your fingers need to be closed.
Dig really hard, kick really hard, and once you feel the wave pick you up, you'll SLYDE all the way to the beach. Remember if you're out in an area where you can stand, stand up and take a break. If you ever feel tired, go to the beach and play it safe.
Also you can switch directions or arms with your Slyde Handboard, so you can go in different directions. However, if you're left-handed or right-handed, it may be more natural to stick with one specific arm, so try both and see what works for you.