Beginners should start with a standing pushup against the wall. Standing reduces joint stress.
Sit on a bench with palms down and arms at side. Rest your feet on the ground with bowed knees.
Put your hands on the ground beside your shoulders. Knees should be comfortable apart. Breathe deeply as you slowly lower your elbows to lower your chest. Keep your core tight.
Fully extending your legs adds weight, making this action harder. Standard pushups have a "ground reaction force" of 64% of your body weight.
Try incline pushups to test your upper body. A solid surface is needed for your hands.
Put yourself in a push-up position. Put your hands under your chest so your thumbs and index fingers create a diamond instead of shoulder-width apart.
Use your finger pads instead of your palms to support your weight. Try to avoid touching your palms on the floor throughout the rep.