How do I use a Keyword shortcut key in Photos

I have added keywords in Photos using the "Keyword Manager". I selected the "Edit keyword" button and then assigned Shortcuts to these keywords. For example given two keywords (Tom, Joe) I added the "1" key to Tom and the "2" key to Joe. How do I then use these Shortcut keys to assign to Keywords to photos? Of course Photos help system was worthless as all Apples help is. I don't understand how you can ad help to a application and leave out half the menu items. It's appalling Apple!