Each steno key, and the key you press for it on your own keyboard. Hold the whole chord, then let go.
The coloured line under each key shows the finger for it. Each hand uses the same colours.
Chord mode reads your keys directly, so turn Plover off first. You see exactly which keys you held on both keyboards, and the chord is checked when you let go of every key.
Plover mode is the real thing. Turn Plover on, click the box, and stroke the word. Plover types it, and the page checks the word it typed.
S can be pressed with a or q. The star (*) can be any of t g y h. Strokes come from Plover's own dictionary.