Move to the lowest point you want to have in focus and "Set bottom".
Move to the highest point you want to have in focus and "Set top".
Set the step size in the entry field to the right, hit return and you
should see the value copy to the left.
Click the "Go" button to start the process.
Most of the other stuff on the gui is for "engineering" use.
The Jog and move buttons are important to find top and bottom
Tom's Computer Info / tom@mmto.org