If these are old plates, exposed a long time ago, I doubt that you will get reasonable results from them.(posted 9712 days ago)Developing will be as for any other photographic material: trays, in total darkness (or maybe a safelight might be safe, depending on the emulsion).
If you want to enlarge them, you'll need an enlarger that will take them. If the negatives are about 1 inch by 1.5 inches, a 35mm enlarger might do it. If they are whole-plate, you'll need a much larger beast.
Do you have any more details?