Light up your profile picture
Change your profile picture to either the Light Side or the Dark Side. You can use a current profile picture or take a completely new one so you can look exactly like Finn in the promo poster (hey, go big or go home.)
Update your status
When you go to update your status today, it will automatically say something like, "Star Wars premieres today, share your excitement!" You can click whether or not you're excited and post to your friends (who would actually choose no?), letting everyone know you're pumped for the new film.
Why is Facebook so excited about Star Wars? It may have to do with Mark Zuckerberg's own personal love for the franchise – check out the adorable photo he posted of his daughter: