The Bar and Staircase pushups are great ways to start working toward your first pushup. Both variations help you start at your current strength level and progress toward a complete pushup as your strength increases.
Place a bar on a rack and put your hands on the bars at chest level with the arms at a 45 degree angle from the body. Keep your body straight and lower yourself until your arms are bent to 90 degrees or your chest touches the bar.
As your strength increases lower the bar and continue to work on your pushup form. Check with a personal trainer to make sure you are performing the movement correctly.
If you do not have a bar and rack available use a staircase instead. Continue to use lower stairs as your strength improves. Before long you will be ready for your first full floor pushup.