Stand up and grab a hold of the loaded hammer curl bar with your arms down and in front of you. This is your starting position.
Raise the bar up until it's a few inches away from your chin or neck. Then lower it back down without fully extending your arms (you should always keep tension in your biceps). Repeat the entire movement for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
Don't extended your arms completely on the downward portion of the movement
Don't try to swing the weight up because this is cheating and it accomplishes nothing
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or load the bar more.
This exercise is one of the all-time classics. It's an exercise that has the potential to pack slabs of muscle onto your biceps if you execute the movement correctly and load the bar plenty.
There is no secret to building big powerful pipes; all you need is to blast your arms with the right exercise and this movement is certainly one of those exercises that will help.
Having said all of the above, we do want to mention one thing that some people have experienced. Namely, some people don't like using the this bar because it causes discomfort to their forearms. If you experience this it is best to do this exercise with dumbbells. No need to suffer in pain if you can just as easily pick-up a pair of dumbbells as a substitute.