My wife died I count her and file joint for 2020 and 2021? Where do you show her death and how do you sign the forms?

Very sorry for your loss.  For the year that your spouse died, you can still file a joint return.  That way, you will get the married filing jointly standard deduction of $24,800 (+ $1300 for each spouse 65 or older) which will lower the amount of income you are taxed on.

In My Info, you will need to indicate that your spouse died. When her name is in My Info,  there is a screen early in the interview that asks "Do any of these apply to [name] ?’” where you will do that, and then a drop down will appear where you can enter the date she passed.

If you have dependent children still living at home, you will be able to file as a qualified widow(er) for the next two years after this tax return.  Post back if you need further help.

https://ttlc.intuit.com/questions/4149272-i-heard-that-the-federal-qualifying-widow-er-requirements-have-changed-and-also-that-states-vary-in-how-this-is-handled