Roundabouts are circular intersections that typically don't use traffic signals to control the traffic. Instead, yield signs are placed at each entrance to the roundabout to alert drivers to approach the intersection with caution.
When you're moving towards a roundabout with a single lane surrounding the roundabout, reduce your speed. You're not required to come to a complete stop before entering the roundabout lane, however, you are required to use caution, keep to the right of the island, and only enter the roundabout when safe to do so. In other words, yield to the vehicles that are already in the roundabout. Additionally, look out for pedestrian crosswalks that may appear in the roundabout. If pedestrians are crossing in the roundabout, you must yield to them as you would in any crosswalk.
If you're approaching a multilane roundabout, you must stay in your travel lane. It is not safe to change lanes while traveling in the roundabout. Therefore, when you exit, you should be in the rightmost travel lane of the roundabout. To safely exit the roundabout, turn on your turn signal immediately after you pass the exit that is before your desired exit, and exit accordingly.