Dressing up. Going to a rehearsal dinner, getting fitted for a tux, and going to the wedding. Then, usually, after the wedding, you go to the reception. No speeches. On the day or near the day of the wedding, though, you generally have your picture taken with the rest of the wedding party. Usually, it's better to get a tux prepared (rented or w/e) before hand to ensure it'll be ready for the wedding. Colors and styles are usually picked out by the bride and groom. It's all it entails. You don't have to be too social. Wait, a paragraph? I've never heard of that. Maybe just a congratulatory thing, then. Do you know what he wants it for?