About gst 3B filling

Dear Sir,

file nil return for GSTR 1 and in GSTR 3B mention purchase details and file it for the month of FEB-20,

after you completed filing your ITC will reflected in your cedit ledger, you can utilize those credit in the month of march GST filing.

1] Open GSTR 3B

2] Open 4.Eligible ITC

3] Mention your detail in column (5) All other ITC {if your purchase is intra state purchase}

Yes I also agree with Mr.  Dinesh's reply
Once he fill Eligible ITC column in GSTR 3B then it automatically  credit shows in his credit ledger.