You would be best advised to print, sign, and mail your income tax return. Be certain that the envelope is postmarked on or before April 15, 2019.
IRS mailing addresses vary according ti where you live and whether you are paying taxes or expect a refund. You can find the correct filing address here:
Form
1040 Mailing Addresses
Alternatively, if you absolutely want to e-file, you can file Form 4868 to request an extension of time to file. If you are going to have to pay taxes, they should be paid before April 15, 2019, even if you are requesting an extension of time to file.