You can either locate a tax professional in your area to assist you in amending the 2020 tax return.
Or -
You can go to the IRS website for the 2020 federal amended tax return, Form 1040-X, and complete the form manually. The amended return can only be printed and mailed.
IRS Form 1040-X (20220) - https://www.irs.gov/pub/irs-prior/f1040x--2020.pdf
