You can file for an extension here: https://turbotax.intuit.com/irs-tax-extensions/ . Remember that an extension is only an extension to submit your tax return, not an extension to pay any taxes owed, If you owe taxes, you will need to pay any taxes owed by the filing deadline (April 15), otherwise you will be subject to late fees and interest penalties.
If you do not owe and will be getting a refund, then you do not need to file an extension.
