Scrape all the crud out of it, next time I'll do it when it's still hot instead of waiting..... ummm a while before doing it.
Sprinkle some salt over the whole pan, just regular out of the cheap cylinder salt.
Last take a lightly oiled cloth and swipe it around in the pan to keep it from rusting. We used probably less than a teaspoon of vegetable oil. If you use too much oil it can get rancid in your pans and that would just be nasty.
If you keep your cast iron in good condition they will last you forever and the more you use it the better they get. Happy scrubbing!