How do I re-enter a checker from the bar?

If you have checkers on the bar, you must use your dice roll to move them onto an open point in your opponent's home board by clicking the checker that is on the bar once you have rolled your dice (points numbered 1-6 for them, which correspond to points 24-19 for you). For example, if you roll a 3, you can enter on your opponent's 3-point if it's not "closed" (occupied by two or more of their checkers).