deep

Hey guys so I have a problem. Whenever I play I have problem with deep pushes. If someone pushes on the backhand side then I also push it back. Since I am a Forehand Dominant player, whenever I try to topspin it the ball goes in the net. Can you please tell me how can topspin this ball properly.

Thank you for letting me join the community. I am still rather new (6 months) into learning table tennis and hope answer more questions tan ask one day!