Follow these steps to understand how you can upload ANX 1 JSON file of the New GST Return, in the Trail version released by government portal.
Login to the GST Portal
Navigate to Services > Returns > New Return (Trial)
Select Financial Year, Return Filing Period, Form/Return and Preparation Mode from the drop-down list
A green message box appears confirming successful upload and asking you to wait while the GST Portal validates the uploaded data.
Click Proceed to ANX 1 to view details in Form GST ANX 1
The government portal may take upto 15 minutes to validate the JSON.