Click on "Federal tax" then click.on "I'll choose what to work on" then visit the W2 section, then there should be a button to add a new w2.
Please follow these steps to add another W-2 if you haven’t filed your return yet:
If you have already filed your return then you will need to see if your return gets accepted or rejected. Please be aware that the IRS currently won't start processing returns until February 12, 2021.
Please see FAQ How to amend a tax return for instructions.