Just a hint to help you out there: a CC3 sheet is analogous to a Photoshop layer. The sheets determine rendering order and can have effects applied to them.

CC3 layers don't really compare to anything in Photoshop, but that's okay because CC3 doesn't have channels, either, so everything stays fair.

For the first few maps, you can probably safely ignore the layers issue. However, they can be useful for isolating certain objects to be edited. For instance, if you call up the Layers window (double-click on the L: <layer> below the toolbar), you'll see three columns of check boxes: select, hide, and freeze. By hiding layers, you can find and manipulate certain objects without having to worry about changing the ones around them. It'll take some experimentation, but once you get used to the CAD methodology, you'll find it quite easy to get what you need done.