How do i file for my father who passed away in june of 2020?

If you know the login and password for your father's TurboTax account (if he used one), log into the account and ask for the 2019 data to be brought over to 2020. Then in the Personal Info or My Info section for your father, there is a check box if he passed away before filing the return.

You will be asked what the date of passing was, because this is printed at the top for the 1040.

Note, if your father filed jointly in 2019, then his surviving spouse should file the return (of course, you can assist, but the return will be in the spouse's name). In the year of passing, the couple can still file Married Joint.

For how to sign, please see this TurboTax Help Article as well as this Community post. You should be prompted at the end how to sign the return and whether or not you need to file form 1310.