Try to get to the shore, dodge the obstacles along the way. Use your mouse pointer to control the boat. The pink arrows will give you a boost. If you want to change the "level" of the game, press your 1,2 or 3 key to see your backdrop change. Multiplayer; Press the Space bar, you should see a second boat appear, to steer it you use the arrow keys, the down arrow key can be used to stop the second boat or make it go backwards if you click it more than once. If you want to then play single player again press the s key to make the second boat disappear.
Raspberry 1.6 Boat Race tutorial