how do I amend my tax return, I messed up and did not add my former employer w2 form. should I be worried?

No, you don't need to be worried, you can adjust your return and fix your mistake.  The next steps depend on if your e-filed return has been accepted or rejected after submitting for e-file.  If your return gets rejected, you can fix the return and re-submit for e-file.  If it is accepted, you will need to amend.

It is too soon to amend your return now. ‌Once your return is fully processed, you can amend as soon as the federal amended tax return form 1040-X is available for filing in TurboTax.  Use this tool to check availability of forms, including 1040X: Tax form availability

Here is some more information on filing amendments: How to File an Amended Tax Return with the IRS