Check the box that says "All official forms required for filing."
The printout will include a page of filing instructions that tell you what you have to attach, in addition to the forms themselves.
Sign it at the bottom of the second page of Form 1040, where it says "Sign Here."
Go to the following link on the IRS web site to find the address to mail it to.
Where to File Paper Tax Returns With or Without a Payment
You should send it by certified mail with a return receipt, so that you can track it and you will have a record showing that they received it.
