Where are the fiction books?
Fiction is not shelved separately. The Library uses the Library of Congress system which keeps books together by subject. Literature (aka fiction!) is generally on the 3rd and 4th floors but are arranged primarily by original language and geography. English literature, for example is class PR while American literature is class PS (see this page to get an idea how literature is classified: http://www.library.illinois.edu/llx/loc.html).
But keep in mind fiction and non-fiction will be shelved together as appropriate e.g. books written by Stephen King will be shelved next to books written about Stephen King.
To find fiction in this library use OneSearch to search by author or title so you can get the call number and floor where the author will be found.