practicing topspin alone

hi sir alois,

i would like to know how to practice topspin alone without any table
i already know anout the shadow play but the thing about shadow play that makes me unsure about this is if the stroke im doing is actually correct
sometimes when i do shadow play i get use to the stroke that i use in it but sometimes the stroke that i use in shadow play is wrong so when i play with a ball and table the ball sometimes doesn't have any spin to make it go inside the table and sometimes it goes toward the net

sir alois do you have another way to make me pactice my topspin???
by the way sir alois I'm a Filipino so I'm not so good at speaking english
sorry for the lame english :DD

thank you in advance :D