The waits tab of the history viewer display waits over the course of the selected timeframe.
The top half of the screen displays a graph and grid showing wait totals for every minute. The lower half of the screen shows a detailed break down of what waits were occuring at each minute.
Clicking on the graph at a point of interest will highlight that particular sampled minute in the data grid below. The grid shows each wait type happening then, starting with the longest waits on the left.
Each grid row is clickable and will displayed a more detailed break down in the lower half of the screen.
The grid in the bottom left displays an ordered list of wait types at the given minute. Clicking on a wait will show the wait type details in the bottom right of the screen.
The "About" box will show you a description of the wait type. The lower section shows global wait statistics for the wait type across all sql servers sampled by miniDBA. This enables you to compare your sql server against the rest of the world and help give an indication if this wait type is something to be concerned about.