This is a typical shutter as viewed from above/behind the camera:


from left to right, there is:
- black plastic triangle, this opens/closes the shutter for focusing,
- X-sync port for flash
- cocking lever (big silver thing), push it to the right to set the shutter
- aperture lever, currently set to f/22
- speed ring, currently set to 1/30
- shutter release lever

Order of operations to compose/shoot is:
- open the shutter
- open the aperture
- focus the camera
- stop down the aperture (any fraction of a stop permitted)
- select your desired speed (WHOLE stops, no intermediate settings permitted)
- check your DOF is sufficient
- close the shutter
- insert the film holder
- cock and fire the shutter a couple times; doing so proves to you that the shutter is closed
- cock the shutter
- remove the darkslide
- fire the shutter
- replace the darkslide
- remove the film holder