can I use my computer to help my son file for his taxes.

Yes.  Do you have the Desktop Download program?   If you are using the Online version you can use the same email for 5 accounts and returns.   In the Online version you have to setup a new account.  If you use your account you will overwrite your return.

You can start another return in TurboTax Online by:

1. Logging out if you are in your account
2. Choose what TurboTax Online product you want to use for the second return
3. Create your account screen
4. Set up a new login for the second return
5. Start working on the new return

The Desktop program can do unlimited returns and efile 5.  You can buy the Desktop Download program directly from Turbo Tax

TurboTax® 2021-2022 CD/Download Tax Software, Compare Desktop Tax Preparation