Back up very slowly and have someone outside the vehicle direct you. Use a series of small turns to steer. It is a good idea to practice this skill off the road in an empty parking lot until you are comfortable with your ability.

To back up to the right, steer to the left. The front end of the trailer will go left, but the rear end will go right. To back up to the left, steer to the right. The front end of the trailer will go right, but the rear end will go left.