There is a good basic tutorial by Peter Pentroski? He posts on this forum and his video is on YouTube. He also has some amazing footage of croc spotting in Florida with his H.
That's a good tutorial, but he leaves out an important point:
You can speed up by bumping the left stick all the way up briefly, and slow down/reverse the course by bumping the left stick down. Each time you bump the stick there's an incremental change in speed.