Dress up like Harry Potter and go "PEW PEW" and other assorted Potter lingo. Then act confused when people get angry at you.

Basically what you do at a book release party is stand around in a line or lines and discuss your favorite thing about ______ book. Then you buy your book, talk more about your book and how excited you are to read it, and then you go home and cry yourself to sleep because you actually attended a party for a book release.