A few pointers:

1. Keep your right elbow tucked into your right side during the backswing (just the opposite if you are left-handed). If your right elbow is elevated it forces you to bring the club up and out to the right side instead of behind you.
2. Most important: Make absolutely certain that you do not sway to the right during the backswing or sway to the left during the downswing. Swaying to the right on the backswing makes it impossible to bring the club behind you, and swaying to the left on the downswing makes it impossible to achieve a full wrist release through impact.
3. Closely study the swings of pro golfers on television and you will see that they rotate around a stationary backbone with no sway in their body position (watch the swing of Tiger Woods and you will see what I am talking about). Try to mimic this with your own swing.

To get the feeling of actually bringing the club behind you during the backswing you should stand erect holding a golf club straight out in front of you. Fold your right elbow in until it touches your side above your right hip and then, without any sway to the right, rotate your torso around your hips keeping your right elbow folded and lightly brushing against your body all the way around. Try to imagine that you are simply rotating around a stationary post (your backbone). When you reach the point where you cannot rotate further you will find your left shoulder underneath your chin and the club fully behind your back and not up and out to your right side. When you rotate back in the opposite direction (downswing), keep your right elbow tucked in and riding lightly against your body. When you reach the point where you are again facing forward your right elbow will naturally straighten out (impact position).

Try this a few times to get the feel of bringing the club behind you and then go to the range using the same method. It will feel very strange at first and will feel as if you are not generating as much power. However, you will find that this method actually generates considerably more power. I have seen golfers add thirty yards to their drives and five to ten yards with every one of their irons once they have learned to bring the club behind them properly without any sway.