Are you Catholic? Do you know how to chant? What, they didn’t teach you in your local parish?
But where to start? The St. Cecilia Schola Cantorum web site has several resources. Start with An Idiot’s Guide to Square Notes – this will teach you how to read the special notation chant has, as well as give you a primer on Latin pronunciation. For the initial chants every Catholic should know, use the “said so” link above. And then – show your friends and parishioners.