If you chose the 'Download all forms and worksheets' option under 'Some Things You Can Do', the first page printed will tell you what forms need to be mailed in and where exactly to mail them.

If not, visit this IRS website since addresses may vary depending on your state www.irs.gov/uac/where-to-file-addresses-for-taxpayers-and-tax-professionals-filing-form-1040 .