First thing I would do is sand that ruff surface to as close to a glass like surface as possible. An angle grinder works well with flap disc. You can nail or screw the pan to a board (using the handle holes) to help it not move around. It is a very messy job (wear a mask of some kind and goggles), but you will love it later.

Next put it on the stove top and just barely coat it with oil on a paper towel. I prefer flaxseed oil for its very high smoke point. Very very thin coat, just enough to make it look wet. Turn the burner on medium high and watch for the oil to smoke, once it starts smoking (it does stink) take it off the burner and let it cool. I usually wipe it one more time when it's hot with the same paper towel just to make sure the oil is spread even. After doing this 4-5 times you're set to cook.

Let it cool before cleaning. No soap in it ever, if you can wipe it out with a paper towel then dont even use water. If something sticks get the pan hot and pour in a some room temp water, that will usually loosen it. Occasionally I use the chainmail type scrubber when I'm being lazy and don't want to reheat it.

Always preheat the pan before cooking, putting something like cold eggs into a room temperature skillet and waiting for it to heat up will stick like glue.

I think that's ot for now. Happy Cooking!