Hey Sweetiele,
Firstly, it’s great you can do the serve with backspin as players usually find the sidespin easier to produce with a reverse serve, with the backspin version being the more difficult to master.
Okay, so how to produce the side spin. When you contact the ball have your bat angle more open and go more around the side of the ball. It’s quite hard to explain actually, we will make a video on this. Watch at 3.20 I am producing sidespin on the ball here: https://tabletennisdailyacademy.com/videos/reverse-pendulum-serve/ See how I am going around the side of the ball during contact rather than coming under the ball. Try to visualise how you will go around the side rather than under.
Hope this helps. Ill produce a video on how to do this soon 🙂
