Tennis Coach Tips : Learn Topspin with High Net training
To learn topspin, you have to brush the back of the ball from 6 O'clock to 12 O'clock ( Low to High). The best approach is to do a C-Swing instead of straight back.
As you can see below, there is an additional high net to improve your topspin. For advance player, the high net will be used for topspin serve.
6 year old Learning Topspin with additional high net training