Is it a historical photograph or a photograph published in a book that someone scanned and posted on line, is it a photograph of something like a sculpture? Is your paper focused on the work of the photographer, the makeup artist who prepared the model, the digital image enhancer who altered the image, the model? There is no single correct way to cite a photograph, because there are many different reasons to cite a photograph. Your instructor would be able to give you more specific advice. In general, though, the 8th edition of the MLA guide would say something like this:
A header must be created at the top right hand corner, and this must have your name, a space and the page number. The section headings used to make the essay readable are not sacrosanct. So, you can twist and use them as you deem fit. You can do the numbering with the Arabic number or the roman numerals. But you must insure that you put a period and a space after the numbering before you write the name of the part of the book. When it comes to headings for books, you will not get any specific system as prescribed by mla. If you decide to make use of one level or system of headings for all distinct sections, you must make them to have a semblance in grammar. This entails that if you use short phrase pointers for headings, then it must be the same for all the headings. This means you should not use a short phrase for some and full sentences for others.