Get staff help. This exercise is named for the stand on which this exercise is performed. It looks vaguely like a preacher's pulpit. From a fully extended elbow position, curl the bar toward your head as far as you can. Pause, then lower the bar to the initial position.
Form is important here.
Don't let your butt leave the bench, and don't lean back, and fully extend your elbows. The form, not how much weight you use, is what is important here. Squeeze it, then return to the initial position. Be sure not to swing the weight and nothing should move except your forearm. This is another shaper that is usually done in a gym on a twin tower multi-station setup with high cable hookups, but it could be done with DBs, only less effectively.