The Home tab gives you a quick glance of any guardrail warnings introduced by you or your team. Since you've done no work yet (nor has "your team") the values in the chart currently show 0 (zero). Click "View all warnings" link to see all guardrail warnings that actually do exist.
Check out the screenshot in my previous response. Does your "Home Tab" match the screenshot? Severe, Moderate and Caution warnings introduced by you and by your team should be all set to 0 (none) however, when you click the green "View all warnings" linkin the upper right corner, that link opens a report that shows you all warnings that already existed before you started the course.