Hi Neal and welcome!
The first thing to do is to go to the right place:
Ebook General > Deals, Freebies and Resources
and make an announcement there, or you can cut straight to the shameless self-promotion thread:
https://www.mobileread.com/forums/showthread.php?t=76829
Next, you should put a link in your signature so people can find your Smashwords page, maybe with some brief info. about your book.
Then you should set up some sort of online presence of your own, like a Web site or a blog. Google have just upgraded Blogger with a whole set of neat new tools, and of course it's free. Your site can inform readers and would-be readers about your work and let them interact with you and each other.
After that, it's a question of how much self promotion you want to do. There's a fine line between letting the world know you exist and spamming ... cross it at your peril!
Hope some of this helps.