All of the normal choices for movement are there, however, if you want to do something other than turn to port during this turn, you'll need to roll a die to check that you'll be able to.
By example, I play a card with a maneuver to port with a -1 on it. What are my actual choices?
As long as your movement includes one wear or tack to the left during your turn (and before any other wear or tack attempts), then you don't have to do anything special.
If you plan on maneuvering in a straight line, you'll need to make one test to do so. That succeeds on a modified die roll of 3 or less, your roll being reduced by your audacity and the modifier on the card (-1 in this case).
If you'd like to turn to starboard, you'll need to make that same test twice, once to override from port to straight ahead, and a second time to turn to starboard. If both rolls succeed, you can (must, really) turn to starboard without having to first make a port wear or tack. If only the first one succeeds, you can (again, must) maneuver straight ahead without first turning to port, but cannot turn to starboard this turn.