You need a third party to submit the request. Since i know who you're marrying (i think) i'll be happy to help. Although im not sure how that works myself either so an explanation would be welcome. :D
on the screen with ID registration is an option called compendium. click on that and just rotate through to weddings. all info is listed there with prices and stuff.
Wow, you know who I'm marrying? XD Anywho thanks for telling me guys. I'll apparantly have to go check it out this wed when I'm off punishment again ><