Retirement tax questions

To be brought to this section in TurboTax Online, once you open your return, make sure to select Federal in the black column to the left and then select Wages and Income (or Income & Expenses if using the Self Employed Version) at the top right.  Then scroll down to "Other Business Situations" - select Show More and then select Start or Revisit for Self-Employed Retirement Plans.  From there, follow the screens to be brought to the section where you can enter amounts for your Individual 401K contributions.  

If you are using the CD/download version of TurboTax, in the Home & Business version, you will need to open your return, then select Business at the top, click on I'll Choose What I Work On, then scroll down to Less Common Business Situations, and you will see the Self-Employed Retirement Plans section there where you can select Start or Update.  

Screens from TurboTax Online Self Employed Version: