How do I file additional returns using my deluxe turbo tax?

The TurboTax online editions can only be used for one tax return per account and User ID.  To start another tax return using the online editions you would need to create a new account with a New User ID.

Go to this TurboTax website and click on Sign up in the upper right to start a new account - https://turbotax.intuit.com/personal-taxes/online/file-your-own-taxes/

The Desktop installed program can do unlimited returns and efile 5 for free.  

You can buy the Desktop CD or the Download program here,
https://turbotax.intuit.com/personal-taxes/cd-download

You can move your online return to the Desktop program without paying for Online.  First save your return as a tax data file from Online
https://ttlc.intuit.com/community/saving/help/how-do-i-save-my-turbotax-online-return-as-a-tax-data-file/00/25740

See how to switch to the Desktop program,
https://ttlc.intuit.com/community/choosing-a-product/help/how-do-i-switch-from-turbotax-online-to-the-turbotax-software/00/26129