Stand tall in a slight step position, the chest expander fixated with your front foot on the ground. Make sure to step hard on it, otherwise it might snap up and hit you. Take the handle with the same side hand where your foot is fixing the chest expander, your palm facing down and backwards, knuckles pointing up. Put the other hand between your elbow and your lower rip. This will help you to concentrate more on the biceps flexion. Now Curl the expander up and release it slowly.
The chest expander biceps curl can be stressful at first for your biceps, so take it slow for the first weeks.