cooking the books

[holy_cats]

I found some great LJ comms here that share TONS of awesome book downloads, and I want to get in on that action, but I can't figure out for the life of me how to get those epubs (or other extensions) onto my iphone, into my iBooks, Stanza, Nook, Kindle, or Kobo readers.
This is baffling me because I have done this successfully before, with all of the Southern Vampire Mystery books. I just don't remember how I did it...
Anyone know?

thanks!