I'll give it a try, Charlotte. First of all, all the events on the Distinguished Guest board are free.
Bakeoffs, whether they are for sonnets, light verse, translations, or whatever else we decide, work roughly this way:
A host, or master of ceremonies, or organizer-type-person, puts out a call for submissions, usually a few weeks before a stated cutoff date. The call for subs tells us what poems are eligible, and how many we can submit, and how we should submit them (e-mail? PMs?) and to whom and by when.
Usually, it's the host to whom the poems are submitted. The host records who sent what, then takes the identifying information off the poems and sends them to the judge. Sometimes the host is a screener and sends only some of the poems to the judge; that can vary according to what the judge wants.
A little time passes in which the host and judge do their deciding. The event proper starts when the poems begin to be posted, usually by the host.
Of the poems the judge gets, he or she chooses the best ten, or once in a while the best twelve. Those are posted here on the DG board. Usually two poems a day are posted, for five or six days. Each poem gets its own thread (identified by something other than the full title, to foil the Googlebots), and the judge adds comments about the poem's good points (and occasionally its flaws). Other people add their comments. Finally, there's a voting period, and a thread on which people list their first, second, and third choices. The host tallies these votes and points, and a popular winner is chosen. Then the judge names his or her top three.
The event we call Deck the Halls is an end-of-year, holiday-season event that's run like a bakeoff even though we don't call it that. It's meant to feature poems that have been workshopped on the Sphere at some point.
Try playing with the features of the board that let you look Waaaaaay back to last year and before, and you'll see groups of threads with numbers; those are bakeoff postings.
I'll stop there and see if there are questions--or rotten tomatoes from those who are sure I've forgotten something.