Take it in small bites. CC3 looks very intimidating at first, and it's a very deep program, but it's possible to make some good-looking maps rather quickly. First of all, don't skip the tutorials--they really are worthwhile.
Second, start up a WIP thread and just start asking questions. I did the same when I first started, and I learned tons that way. Here's my first thread:
CC3 Continental Map: The Northlands
Welcome to the Guild!