The push press lift is a lot like the military press/overhead press, so if you are accustomed to the military press you should have little difficulties with the push press. The push press is a lift in which you lift a barbell over your head, but at the same time when you are pressing the bar up you are pushing up from the ground with your knees. Your knees bend a small amount, but you push up when you press the bar up in one single motion. It is better explained and better learned visually, so watch this tutorial!
Follow what you see in the video and listen what you are instructed in the video too. This lift is suppose to be a heavy compound lift, so make sure you are lifting heavy but at a comfortable amount of weight. Technique is key here, like all previous lifts I have covered!