Glad to hear you've signed up for a photo course. You have questions that really need to be demonstrated rather than explained. What you should get from the course is how changing ISO, shutter speed and aperature affects an image. (It's much more than just lighten/darken the image.) Once you know and undertand those three thing, you control the image!
OK, before I answer your lightning question, let me say this....
IT. IS. EXTREMELY. DANGEROUS!!!
Ideally, you should be inside a structure (house, barn, skyscraper) shooting from an open window. The second choice (and since I was sixty miles out in the desert, the method I used) is a vehicle. Put the camera on a tripod outside the vehicle and used a remote shutter release. Don't use the self timer here. You do not want any part of your body outside or touching the metal car body while there is lightning around. If you can hear thunder, it ain't safe. My settings were ISO 200, aperture f8 and 30 second exposures. You won't get lightning on every shot but if you shoot the entire storm, you should get a few. Look for rain falling below the clouds. The lightning usually uses that rain as a path to earth. Aiming the camera for that rainfall should increase your chances of getting the bolts. Since I was way distant from any lights, I could do long exposures. If you're in town (and lightning over a cityscape makes a very nice image) you'll have to shorten the exposure. You could try two fifteen second exposures, three ten second, five six second, etc. Whatever is appropriate for the image you want. Search for lightning images to get an ideas for where you would take pictures, mountain, city, lake, whatever. BE CAREFUL!
