The captain himself may appear on the reel as a wild card. This means he can replace any other symbol and help you get more winning combinations on the entire reel. Remember that the captain only appears on reels 2, 3 and 4.
First look at the command bar at the bottom. Use the bet button to increase or decrease the number of coins you wish to bet on the next rotation. Keep in mind that larger, more risky bets can also trigger a larger drop. If you feel particularly lucky, the Bet Max shortcut will allow you to push all in with just one click.