Take a good photo of the item to the paint department of the home improvement store and ask them what will work for you. They have the best selection, the most up-to-date materials and most important, the most informative sales staff to get you what you need for a professional job and can help figure out what is going on.
Remove any peeling paint. Sand smooth, prime, and paint with metal paint.
You would need to sand all the old paint off. Then add primer and re paint.