Understanding the Dashboard
The dashboard is a simple view of the current activity related to campaigns that you had running over the last 30 days. Its a great snapshot view of how things are going.
The dashboard will only show data however if you have campaigns that have been applied to outgoing mail.
Clicking on the campaign names in the graph legend will turn those data series on or off, allowing you to see details for only specific campaigns you wish to.
If you require more detailed information about the activity of one of your campaigns, you should try out the Reports page.