Just getting into vert skating? This is where you want to start.
Drop in and do a forward (frontside) stall on the coping. Keeping your weight above the coping (so you are just standing there), turn your waist at least a quarter of a turn and look directly down the ramp. Using your head to keep you going the right direction, do a little hop straight up, and turn followin you upper body. Just be careful not to push off too much or you will miss the transition.
This is a basic, basic trick. As you drop in and head up the other side, turn quickly as you hit the coping so that you will land in a 'backside' stance. Make sure to look down at your feet, so that you can spot your landing, and be careful to keep your weight above the coping. Otherwise you will fall down and hurt yourself.
If you are a beginner, and have learned the stalls, you can actually make a 'run' out of this! There are several different easy variations of stalls. For instance you can stall on only one foot - you can stall on one foot, put the other down on the coping with the toe pointing the opposite way, and then lifting the first foot, and putting it beside the other in a backside stance - you can stall on the coping with your soul foot in either regular soul or topside soul - and many more!