online.i did online.as a new tax payer .you must have a PAN.but you must know about your are code range code etc.you can get information regarding this from your regional gst office.you should have a current account in your firm name in any bank.to open a current account you should have proof of business & place of business .for proof of business self declaration on court paper,CA certificate,udyog aadhar certificate etc required.for place of business electricity or telephone bill on proprietor’s name required.you need to upload required documents on gst.gov.in as a new tax payer.select e commerce seller in business description.if everything found correct.regional tax officer will issue gst number with certificate in next few days