Welcome @oldskeetshooter Bill,
You add the column for Tags to the right of the last column in the Transactions table (tab). You can manually populated the cell and / or use AutoCat rules to populate the cells. If you decide to use AutoCat for Tags you will need to add a column in that Tab too. There are two Excel community solutions that I’m aware of that include Tags as a criteria selection; Transaction Tracker and Tags Report. I use Tags to identify what I have determined to be my recurring Bills.
There is a Google Sheets solution called Using Tags in the Categories Sheet. I don’t believe that has been created yet for Excel.
Clint