Hi, no worries, you'll be able to fix this! If you are unable to e-file by tonight's deadline of midnight on 4/15, you can file an extension. If you wanted to file by mail, you'd have to get your tax forms postmarked today, so you are likely too late for that.
Please see this FAQ for how to file an extension using TurboTax Online: https://ttlc.intuit.com/questions/1901031-how-do-i-file-an-irs-extension-form-4868-in-turbotax-online.