Execute topspin pendulum serve

I looked at the video tutorials online saying how to do this standard topspin (top/sidespin) pendulum. And they usually say to contact the ball at the middle-back at the 9 oclock position. But from what they show, the contact is quite flat like a flat hit, so i am not sure how hitting the ball at the middle back WITH A FLAT CONTACT will generate the topspin? 

Furthermore i've heard people say to come upwards on the back of the ball, but when i see the serve in practice it seems like a very flat hit on the back of the ball, and i don't see them coming upwards

For example backspin, I can understand the idea, since you make a whip like action with lots of wrist, contacting at the bottom in order to get it to spinning a lot, so isn't the ideal point of contact on the top of the ball and going forwards?

Hi Aaron,

You don't need to brush up the back of the ball much to get the topspin.  Just a little upward movement will add to the topspin on the ball.  The ball will already want to rotate forwards anyway with a flat serve so a small upward movement will generate topspin.