Teaching a 3 year old to ride a bike...any tips?

[LaDY]

For my LO's birthday we got him his first bike...bless him he loves it, the only problemt being that he doesnt know how to ride it! It has got stabilisers on however he doesn't seem to understand that you have to push the wheels one at a time, he seems to do it with his right leg but not his left! I am trying to help him but i find myself getting frustrated! Agggghhhhhhhh!!!! Any tips? xxx