Do not move your elbows when performing these. Moving the elbows forward will take stress off of the biceps at the top of the movement. The start to curl the weight up. When you get to about s of the way up, turn your pinky towards your chest. Then lower the weight in reverse.
Preacher curl bench and a curl bar or dumbbell.
First you want to adjust the bench to your height. There usually is a height adjustment on the pad. Just raise it up and down. Your arm pits should be resting on the edge of the bench. You want to adjust the bench so that you can fully lower the weight, without hitting the rack.