If no payment, you shouldnt need to do much more than mark the EF box in Part VII of the fed info worksheet, then mark the Freeze box on the form and enter a zero for the amount youre paying with it at the bottom of the 4868, .  

If youre making a payment, you do have to do a bit more work, here are the instructions

https://proconnect.intuit.com/community/electronic-filing/help/filing-an-individual-extension-form-4...