Once you know how to sports bet on FanDuel, you can take advantage of promos and get free credits. These credits are like free cash. The only caveat is that you can't withdraw it. What you can do with it, however, is make bets. As long as you state that you're using free money on the bet slip, it will be treated as a real wager and, if you win, the profit will be credited to your account in cash.