This is a variation of a regular push-up. This version takes some weight out of your arms and chest so that you can complete more repetitions.
Place your hands on a step or bench.
With your arms straight, your shoulders should be over your wrists and your hips should be over your knees.
Bend your elbows and lower your upper body slowly to the ground. When your chest reaches the the bench, press up with your arms and return to the start position.
Perform 8-10 repetitions.