Getting access to this much data at once can feel overwhelming. As with anything, take one bite at a time.
Within each App there will be a list of ready-to-go Reports. Within each report there are several pages for that report. Do not think you need to understand each report day one. In general, we recommend choosing 2-3 reports that are specific to your role and dig in, understand, drill through, and take action. As you make organizational changes, watch the Trends change.