You can select a treshold value for speed (default 5 km/h or mph); statistics for speeds above and below the treshold value are displayed separately (resp. "Moving" and "Stopped"). The idea behind it is to filter out pauses.
Click & drag with the mouse cursor on an area in the graph to zoom in.
Double click the graph to zoom out.
Hold shift or alt and click & drag to scroll a zoomed in graph.
Hover the mouse cursor over a point in the graph to show the data.
Click a point in the graph to zoom in on that particular track segment on the map.
Hover the mouse cursor over a track segment to show the data.
When you click the button "Track data" a new window will be opened with a table that shows the data of all track points. You can copy the data with Ctrl-A & Ctrl-C (Cmd-A & Cmd-C on the Mac) and paste it in a spreadsheet.