On what page is the following quote? “They grew up on the outside of society. They weren't looking for a fight. They were looking to belong.”

The quote that is listed in the question does not appear in Hinton's book The Outsiders; however, the lines do definitely describe the Greasers.  That quote is the tagline from the 1983 movie version of The Outsiders.  The movie version is a fairly strong book to movie adaptation.  Additionally, the movie's cast is basically a who's who of current Hollywood stars.  Rob Lowe, Matt Dillon, Diane Lane, and even Tom Cruise appear in the film.  

A strong hint to readers that the quote mentioned in the question is not taken from the book is the fact that the people referenced in the quote are referred to in the third person.  Readers of Hinton's novel would correctly assume that the "they grew up on the outside" refers to the Greasers.  They are outsiders in their society.  Readers would also remember that the book is narrated by Ponyboy.  He's a Greaser, so he wouldn't refer to his own gang as "they."  He would have said "we."  If the quote was from the book, then it would likely have read as follows: “We grew up on the outside of society. We weren't looking for a fight. We were looking to belong."