What forms do I mail in after just completing my taxes. The 1040-V? Along with which forms?

not completely true.  if you owe money and didn't select direct debit, you must mail in 1040-v along with a check.

If you didn't select e-file, then you have to mail the entire return; the instruction page will tell you what to include and where to mail your tax return.  If you select e-file, you don't have to mail anything if you pay your tax bill through direct debit.