Hello @mary53 ,

Once you have installed QB Pro 2021, you will go to File, Open Previous Company.  You will then have to navigate to the location of your QB 2020 data file, ending in .qbw.  Once you choose this file, a window will appear telling you that your company file must be upgraded to the new version.  Once you agree to this, the upgrade process will begin.  It doesn't take long but is dependent on the size of your company file.

Before doing the upgrade, I usually locate my company file in the QB 2020 location e.g. Company Name.qbw, and I make a copy of it in the location where I want the QB 2021 file to be.  That is the one that I allow QB 2021 to upgrade.  That way, if anything goes wrong during the upgrade process, you will still have an intact 2020 file that you can open with the 2020 software, if necessary.

Hope that helps!