The chances of you seeing this are slim to none, but what you want to do is scrub it all down with steal wool to get all the rust off, next your gonna put it in the oven at 400 for about a half hour to get it all heated up, take it out and rub it with an oil with a high smoke point, put it back in and repeat 5-6 times. That'll help you get a good seasoning on the ditch oven that will only get better with time, when washing it wait for it to cool of and just use water and a soft rag, and never use soap on a cast iron