Once a return gets filed, the only way to make changes is to file an amended return (1040X). You can do this thru TurboTax. But you'll need to wait until your original return has been processed and any refund issued. Then you can file the amended return and add the missing items.
Here's a link to the TurboTax support page on amending returns, which will get you started: https://turbotax.intuit.com/tax-tools/tax-tips/IRS-Tax-Return/Amending-Your-Income-Tax-Return/INF120...
