Kneel down on your knees and rest your (extended) arms on the floor wider than your shoulders. This is your starting position.
Lower yourself down until your chest is a couple of inches above the floor and then push yourself back up to the original starting position. Repeat this movement for the desired or prescribed number of repetitions.
Perform this exercise in a smooth and fluid motion
Don't lock out your arms at the top
SPECIAL NOTES & LEVEL of DIFFICULTY VARIATIONS
To increase the level of difficulty, slow down the movement or cross your legs at your ankles.
This exercise is great for beginners who are just starting out at the gym - men or women. It's also a good warm up exercise for those who are about to do some heavy lifting and do a chest workout. The fact that the knees are down on the floor doesn't mean that you are cheating, it's simply to reduce the amount of pressure or difficulty level.
To make this exercise more challenging all you have to do is raise your knees off the floor and do a regular pushup. Once you do this the exercise becomes twice as hard.
You can introduce variety and increase the level of difficulty by keeping your knees down, but widening the placement of your hands. Wider positioning will make it more challenging. It will also "hit" your chest muscles from a different angle which is a good thing as well. Conversely, if you place your hands very close together, you will be targeting you inner chest area.
Thus, you can perform 4 or 5 sets of this exercise and with each set you can change the placement of your hands. That way you will be hitting your chest from a myriad of angles that will result in optimal muscle exercise and development.