This is a stand-alone form so it can be filed all by itself by completing it, sign it and place it in the mail.
You can use your TurboTax account to complete the form by saying you want to amend your tax return (you're not really amending it), but you can access your return to complete the Form 8606 and print it.
Sign into your TurboTax account and then select "Take me to my return". Select "Amend (change) a filed and accepted return" to continue.
The IRS direct links to the form and instructions are included here for your.
This TurboTax article can provide assistance and information to help you as well.