Hahaha no, no sharks around here.
erm well it's all about balance obviously. Most people only take a few attempts to get up, if you can snowboard, skateboard or surf then the concepts are the same.
Everyone's posture is terrible to start until you find your balance and get used to riding sideways and are able to stand straight properly, plus you can move your bindings around the board at different angles so you're comfortable. Bear in mind that you are strapped into the wakeboard so when you fall the board goes with you, catching an edge and face planting can be very very painful - I'm a master at it! But like anything you get back up and keep trying till you get it right.
Have a look at the clips on this site:
http://test.waketrix.com/
Very good explanations.