Whether using matrix or center-weighted or spot you should keep in mind that the camera, not you, is deciding where middle gray is -- when you point your spot at a specific part of the frame and the camera sets the exposure, say, to f/8 at 1/500th of a second, that area of the photograph at that exposure will be at the middle of the tonal range. As PKR points out, with b/w film, you want to cheat toward overexposure if you have shadows or dark areas twhere you wish to retain details. So -- you can use any of those settings effectively AFTER you learn how they work and what the results likely will be -- then you can work around their weak points. For now, just experiment -- oint the F100s spot at various parts of a potential image and note how much the exposure changes; and visualize what the image will look like if that specific spot is the middle of the range -- will the blacks be too dark, or the whites too bright? Figure out which is the correct exposure for what you want for that image. Then change over to matrix and see what exposure it selects. It's very good metering system and you'll see whether it picks "right" most of the time or not. Most of hte time, I suspect, it will. When it doesn't, figure out why, and learn to watch for those conditions so you can correct for the camera.
Read Ansel Adam's book "The Negative." You won't understand much of it. Keep working, studying, go back and read parts again. Repeat this for several years. You'll get really good.
I found when I was starting out a few years ago that as I learned I wanted to control my own exposure and learn from that process. I used meterless cameras with handheld meters or using Sunny 16 rules outdoors in daylight. Now I feel I know at least the basics very well, and I have no issues with Aperture priority autoexposure and other automation but I intuitively compensate for that system's prejudices.
