I forget the exact quantity of shredded cabbage (don't use cores) to about a tablespoon of coarse or pickling salt, but it would be at least 8 cupfuls of finely shredded cabbage. The secret is to use your hands and mix in the salt with each layer before adding the next. Once you're done, weight the works down with a plate that just fits the crock/container and sit a tied bag of water on it. Or, just use several tied bags of water to hold it down. There's no need to add water to the cabbage as the juices will soon start to come out. Cover the container with some cheesecloth or a clean linen towel to keep out fruit flies. Check in a few days and make sure there's enough juice to cover the contents. If not, then add just enough water to cover but no more.
Check once a week on progress and remove any bits of mold that might form. These are harmless. It depends on your room temperature as to fermentation time, so it could be about 4-5 weeks on average. To test for doneness, remove the moldy parts on top, carefully dip into the 'good' part and taste. You'll know when it's ready or if it needs a bit longer.
If ready, you can either remove the top layer of moldy stuff and simply keep it weighted down. Occasionally you'll need to remove more moldy tops.
Or, you can do as I do - put the clean layer into a large stock pot, add just enough water to cover, heat to almost boiling, divide into clean bottling jars, cap, and hot water bath them for about 20 minutes and then cool. This stops all further fermentation and will keep for years. To use, simply add the contents to your cooking container and add your choice of seasonings but check the saltiness first before adding any. As is, is usually just enough. And then cook as desired. If you want to panfry the kraut, first drain off the water.
The mennonite community near me make huge quantities of it in used olive barrels, the 55 gal types. I don't envy the ladies having to shred the cabbage by hand (they don't use electricity).