How do you sail?

[searage]

you do have access to grape shot, chain shot, and even the flaming shots by level 8! you must first buy them from the cannoneer in port royale, then while shooting your cannon instead of the right mouse button, use the mouse scroll wheel to cycle through your available shots.

oh and the next thing you learn for sailing is "Turn About" (i think is the name) that lets you spin extra fast for a few seconds.