I am new to Salesforce and I am making my way through the "Learn CRM Essentials" training module.  When I attempt to launch "My Trailhead Playground 1" in "Navigate and Personalize Salesforce", I get a new browser window with the error message "Sorry, that page doesn't exist. Try retracing your steps or review the URL."  What am I doing wrong?

I am new to Salesforce and I am making my way through the "Learn CRM Essentials" training module.  When I attempt to launch "My Trailhead Playground 1" in "Navigate and Personalize Salesforce", I get a new browser window with the error message "Sorry, that page doesn't exist. Try retracing your steps or review the URL."  What am I doing wrong?