The TurboTax online editions are only for completing one tax return per account and user ID. You can have up to 5 user ID's associated with an email address, but can only complete one tax return per user ID. To create another tax return using the online editions you must also create an new online account with a new unique user ID.
The TurboTax desktop CD/Download editions include 5 free federal tax return e-files (set by IRS rules). Any federal tax returns beyond 5 can be printed and mailed.