You can enter on July 1st right here on this blog. There will be a new page available at that time.
The rules are simple. You must be 18 or over (no real children in my R-rated books, no way, forget it). You can choose any character name you want unless it's obscene, and I'm the judge of that. And you must agree to die, possibly in a gruesome manner, in the book, and not be upset about it later, as in sue me for damaging your tender psyche or something. The role you play is completely at my discretion, but the only things for certain are that you'll have a multi-page, speaking role and that you won't be in the next book. You'll have to sign a short release covering these points.