The Kardon was a copy of the screwmount Leica III series cameras, with some improvements. The basic operation should be the same.
Shutter speeds have two dials, one for high speeds and one for low. You should only change shutter speeds when the camera is wound; do not change them after firing the shutter until you wind the camera.
You change the high speeds by lifting the dial on top of the camera and turning it to the speed you want then letting it drop back into place.
You set low speeds by first setting the high speed dial on top of the camera to 20-1. Then you set turn the low speed dial on the front of the camera to the speed you want. When going back to shooting with high shutter speeds, the front dial should be set to 20.
Loading film, rewinding and using the rangefinder should be the same as for a Leica III, IIIb, IIIc or IIIf. Manuals for those are easy to find.