Previous years sales effect in Gstr9

Sir,

19-20 sale shown in 20-21 Gatr-1 and Gstr-3B, and tax paid in 2020-21.

I want to know the treatment in Gatr-9. And this is the first time field Gstr9 for this company. Please suggest me the treatment.

Thanks in advance
Regargs
Avishek Mukherjee