Which 1040 do I fill out to claim my stimulus checks if I wasn’t working? I received the first stimulus but not the second or third

If you were being claimed as a dependent then you were not eligible for the Economic Impact Payments.

You will have to file a 2020 and 2021 tax return for EIP2 and EIP3 and the complete the Recovery Rebate section for the stimulus payments.

To complete and file a 2020 and 2021 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the desktop editions for each tax year required from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/

A 2020 and 2021 tax return can only be printed and mailed, they cannot be e-filed using TurboTax.  Use a separate envelope for each tax year when mailing.