Next take the bar in hand with your palms facing down. That's right, just like your handlebars. Next, pin your elbows to your sides. During the curl, the only thing that will move is from the elbow down. With the elbows pinned, lift the bar up to about 45 degrees from your body.
Most people can lift it a little higher than that.
If you can lift it higher without your elbows lifting off of your body, go for it. Major muscles worked her are Bicep, and Brachioradialis, and several extensors along the back of the forearm. All of these exercises should be done in a slow and controlled motion. Remember, form is always more important than the amount of weight that you lift. Done incorrectly you risk injury and it is basically wasting your time.