If you could not e-file you will need to file a paper copy of your return. Do not forget to staple copies of your W2s to the front of the first page where indicated and do not forget to sign and date the return. Here is where you will find the address to which to send the return based on the state in which you are located and whether or not you are including a payment with the return.
https://www.irs.gov/uac/where-to-file-paper-tax-returns-with-or-without-a-payment
