You need to write a backend for this form. As you can see, this form allows uploading a file. Here is what your backend should do: if the uploaded file is a valid image - print MD5 hash of a file (in hex form, upper case, e.g. DDE2F145B096BDD08360E9F9821831BC). Otherwise print "Not a valid image". It's ok that output will not be an HTML page, just print a single line. NOTE: you can assume that image will always be either JPG or PNG, but if your code accepts other formats - its ok.