Try browsing these Dewey Decimal Call Numbers:

Books on mythology and folklore are in two different sections of the library because myth is a sacred (religious) narrative, whereas folklore is secular (not religious). There is some overlap, so if you're not sure, check both. 

• Mythology: 290                     
• Folklore, fairy tales, & legends: 398 
• Graphic Novels: 741.5 - exact area depends on the nationality of the author
• Children's literature & pop-up books: 741.642, in the right, back corner of the library, by the magazines
• Literary fairy tales & fables: 810-899 - exact area depends on the nationality of the author