Are you channeling your best self with this comment? (If you're not sure, check out our Code of Conduct.)
I'd wash it with hot soapy water. If the spots are rust I'd take an SOS type pad and scrub off the rust. Then immediately place on a hot stove burner and cook off any water. When the pan is hot turn off the burner and place some vegetable or olive oil in the bottom of the pan. Let sit for an hour or so to cool the pan. Then use a paper towel to wipe off the excess oil and it should be ok. If the rust reappears you need to follow the same procedure but then season the pan by placing in a warming oven with the oil in it and letting it 'bake' for a few hours.
Good advice above, but you may have to use fine steel wool to remove the rust spots. And I'd season it right away by wiping with oil and baking it. Fry some bacon in it after to help it along!
I thought I had ruined my grandmother's old cast iron pan by burning salmon skin in it and was devasted. A clerk at the Le Creuset store suggest two things: (1) boil a mixture of vinegar and oil in the pan and then (2) scrub a mixture of olive oil and a generous amount of kosker salt into the pan using an old dish towel. These methods worked great for me.
Sorry - I made an error above. Boil a mixture of vinegar and WATER not oil. My bad - Sorry!
From basil to tahini to sour cream...
Strawberries' New Sidekicks
Easy Make-Ahead Lunches
What's Topping Lists
Ultimate Stove Cleaning Guide
Grow an Entire Pizza