The first step of the serve progressions is learning how to swing up at the tennis ball correctly. In the serve fundamentals section of the website, steps #8 and #9 discussed how good players swing. They start by swinging up on edge. About halfway through their swing their racket and hitting arm form an “L” shape. Finally, right before contact they pronate (hyperlink) to hit the tennis ball.
At 47 seconds we start to learn this motion. My entire body is facing the net and I have the tennis racket resting on my shoulder on edge. The first step is very simple. All you need to do is swing up on edge like you are trying to use the side of the tennis racket to hammer something into a wall.
Once you have the above motion down, then you can add pronation. I do this at about 1:30 in the video. I start by swinging up on edge and pronate right before my imaginary contact point.