With a manual camera (assumed, as the Yashica Model J isn't familiar to me), pushing and pulling are just a matter of setting your external meter (hand held meter, smart phone app, or Sunny 16 rule) to a different Exposure Index (EI) than the ISO speed of the film that's loaded in the camera.

So, you've loaded Tri-X, ISO 400, but you're shooting in a bar late at night, and it's pretty dark, so you decide you need to push to EI 3200 in order to get hand held shutter speeds. All you do is set your aperture and shutter as if you had 3200 speed film, and then mark the cassette after shooting to remind yourself to process with a three stop push.

Bottom line, the camera itself has nothing to do with "pushing" or "pulling" film, it's the metering. In some cases, the camera has a meter, which you can set (or which sets itself, by reading the DX code on the film cassette), and changing this setting will, for automatic cameras, cause them to treat the film as faster or slower than its box speed. But for cameras without internal meters, it's up to the photographer to set whatever metering device is used.