The top dial knob when pushed in starts the stop watch. When pushed in a second time it stops the stop watch.
The bottom dial knob when pushed in resets the stop watch.
And the bottom middle “mini” clock (on the face of the watch) shows how many seconds the stop watch has been running.
The top left “mini” clock (on the face) shows how many minutes the stop watch has been running.
As for setting the time, the top right “mini” clock shows how many hours military time in the day. As you set the time in your watch (using the middle knob dial), you also set the hour of the day.