1- Stand midway between the pulleys, grasping the D-shaped handles with underhand grip and your arms outreached in shoulder level.
2- Now inhale and curl the handles toward your head.
3- Exhale and slowly revers the move to the starting position, and repeat until you finish your reps.
Tips and Advises:
1- Don't allow your body to swing in order to help you with moving the handles.
2- Keep your upper arm steady in their starting position as possible to focus the effort more on the biceps muscle alone.
1- Biceps Cable Curl
2- One Arm Biceps Cable Curl