Going back to your original question, after you are connected to your Lion Scout in Scoutbook, you should see his name when you go to My Dashboard -> Administration (his name will be under “My Family”).
After you click on his name and go to his main page, you can scroll down and you will see some options that look something like this:
Because he is a Lion Scout, his Den Leader is probably asking you to go to his [Scout]'s Advancement
page, click on “Lion”, and then you can click on any of the Lion adventures that he is currently working on. When he works on requirements at home, you can mark them as Completed in Scoutbook.
For example, if he practices tying shoelaces at home, you can go to the “I’ll Do It Myself” Lion elective adventure, and click on the box next to requirement #3, then add the date completed and Save.