I'm entirely new to modding, especially of Bethesda games. I don't know what I'm doing, but I should like to learn.

My question is this, since it will determine the direction of my learning:

Can I or can I not use the creation kit to add landmass to the game? I mean not islands and such, but entire continental regions to the north, south, east, and west? Entire new map areas?

Yes*3

... but only with the help of third party utilities, unless you plan to build the entire continent in the landscape editor (i.e. not draw up a heightmap in Photoshop / whatever and import it), it would seem.