If there’s no visible last name (like Johnny Craig), then the writing on the cover is probably NOT an autograph by anyone associated with the book, I’m guessing it was put there by a previous owner, which isn’t uncommon for books of that vintage. Other than books from authenticated pedigree (original owner) collections, which this is not, writing on cover is a defect that will lower the grade of your collectible.

Finally, I don’t know where you live, but you might want to show your book to some local comic book store owner or to comic book dealers at a comic book convention and they can assist with determining a grade and helping you price your copy.