I received a w-2c for my Maryland taxes, one #16. How do I amend the return?

If you need to amend your return, you will see an option to do that on your home page when you log into TurboTax. Look at the bottom of the page, under Your Tax Return and Documents. Click on the year you want to amend and choose the Amend (Change) option. Once in the amended return mode, access the W-2 entry you originally made in the Wages and Income section, and then Wages and Salaries. Edit the W-2 entry to reflect the corrections and proceed through the menu options in the amended return routine. Depending on what corrections were made, you may find your tax is unchanged, in which case you may not need to file the amended return.

You should wait until you receive your tax refund if applicable before you amend your return in case the taxing authority changes it for some reason.