Rasana Atreya wrote a FAQ about Self Publishing Basics, on her blog, On Getting Published, Good Books, and Living Goddesses: Publishing Trends, e-books, Literary Agents
You will learn many things you need to know, but expect to visit FAQ more than once so add it to your bookmarks. It takes time to absorb what she explains, such as the following:
* Amazon, Barnes & Noble, Apple etc. are vendors that you may use to sell your ebook.
* CreateSpace does paperbacks. Paperback formatting is very different from ebook formatting. While you can get away doing your own ebook formatting, or have someone do it for you on the cheap, paperback formatting is way more complicated - and expensive.
* Smashwords is an aggregator.
Rasana said, "... there's more on this in my FAQ. "