You do not have to appear. - I believe the court form can be downloaded from court web-site. If you have any problem, and you should contact a local S.B. attorney.
This is not intended to be legal advise or as legal representation. I am a California personal injury attorney . Be aware that every state has its own statute of limitations; and statutes & case laws that govern the handling of these matters.
I would also add that an "expungement" in CA is not what many people think it is. The court will add "dismissed" to your docket after a 1203.4 dismissal, but the charges will still be there.
You can mail it in. Follow the link Mr. Makler sent you. Please be aware that there is typically a $120 fee charged by the courts to process the application. Based on what you've described, hiring an attorney shouldn't cost you much more than $500, and should make the entire process much more smooth and efficient. Good luck.