The uploads tab is a place where you can stick any tax related form you may have gotten in the mail (other than 1099-miscs).  W-2, Student Loans, 1098, mortgage interest, Bank interest, 1099 INT, 1099 Div, Stock trades. Stuff like that.

If you don’t have a scanner you can take a good, clear picture and upload it with your phone or camera.

Huzzah!