It all starts with voting in the polls in the individual sections, and when the voting period ends, the 3 users who get the most votes in the categories there then get nominated in those same categories in the main MOTY poll which can then be voted and the member who gets the most votes wins that category in the poll.
Nah that's not how it works this year. This year there are the section-specific categories, that go in their respective sections. Later tonight the official MOTY thread will go up, which will have the overall categories, and you vote for the overall categories there. Everything specific to one section will go in that section and nowhere else.