You need to visit an auto parts store that sells painting compounds. Pepboys does, and I’m sure others do. They’ll be labeled by micron size, and the media will be the proper type.
Harbor Freight sells stuff for polishing materials other than paint, such as various metals; aluminum, copper, steel, etc. You do not want to use those polishing compounds. Go at your paint with an aggressive compound designed for polishing steel and you’ll quickly end up with a naked but well polished area on your hood.
But first, visit the local bookstore and pick up a book on painting cars. In general, you’re going to want to start with a larger micron size and work toward the smallest. But there are other things to know, such as pad types and uses, and how to use the buffer to prevent swirls. So get the book. It’s worth every penny the $10+/-.