The description of the manual focus is available in part 2 of the manual, page 40. The manual is available as a PDF here: http://ca.konicaminolta.com/support/manuals/film-cameras/film_af_slr/index.html#si_series
. It is the seventh camera in the SI series in the list.
To manually focus the lens, press the focus-mode button on the front of the camera (bottom left when you are behind the camera) until M. focus appears in the data panel. If you have an AF lens, turn the focusing ring until the subject appears sharp. If you have an xi-Series or AF Power Zoom lens, pull and turn the lens control ring.
The focus indicator will light when the subject is in focus. To return to autofocus mode, press the focus-mode button again. The camera will also return to the autofocus mode if you press the program reset button.
I hope this helps.
(in manual focus, you can take a picture even if the subject in the focus frame is not in focus. Often it means you need to take multiple pictures to get a good shot of the subject. The advantage is that you can get some interesting shots.)