It's important to note that deck plans in Cosmographer 3 for CC3 work differently than they did in Cosmographer 2 for CC2 Pro. In Cos 2, different decks lived on different sheets within the same FCW file, but since sheet effects were introduced in CC3, Cos 3 deck plans now put different decks into different FCW files which are then linked together.

I haven't seen any tutorials for Cos deck plans other than what is in the Tome of Ultimate Mapping (for CC2 Pro/Cos 2), and nothing for Cos 3 to date (the Cos 3 Essentials Guide PDF hasn't been released yet and CC3 Help doesn't have any Cos 3 support yet either).

There was, however, an issue of the Cartographers Annual Volume 1 in August 2007 that features starship deck plans that work similar to what is now in Cos 3 and that includes a PDF tutorial on making deck plans.