Sure, splatter it on social media. But don't smother your friends in your fantastic accomplishment. They'll weary of seeing it, hearing about it, and listening to the broken record, A Deadly Suggestion - R.W. Williams. You must seek out new undiscovered support. Somewhere out there there must be a multitude of unknown murder mystery readers. You just have to find them. You also have to let them see and read about your book more than once. You want to let your newly minted potential clients know that not only does your book exist, but it is popping up everywhere.
Now I am going to give you a gift, my keyboard flangernoggins. http://freebookreviews.blogspot.com/2011/07/promote-your-book-indie-author.html Just this one page alone will keep you busy for hours . . . no! Days! There is so much information in this one page of this website, http://freebookreviews.blogspot.com/ that I can promise you the need for Dramamine by the time you are finished looking at it. Where to begin will be your first thought. Hint: Start at the top of the page, first suggestion, and accomplish just that one thing. Then move on.
Just by reviewing the first suggested link and first implementing the items you know how to do will put you on your way to a broader base of possible readers. Hopefully you are not like me, a technological dunce. But if you are a kindred spirit, by first doing the things you understand you are taking steady steps forward. Then go back through the list and find things that you aren't so certain about implementing, and ask someone how to accomplish the next listed goal. Remember the old saying, "Ask and ye shall receive."
I think of a written but unpublished book as someone laying in bed. When it's published, it's like someone finally sitting up on the edge of the bed and putting their slippers on. What do you want? You want your book to be like that incredible go getter guy who jumps out of bed, into the shower, throws on his clothes, grabs a mug of the stiffest coffee he can find, and roars down the freeway to the job he just can't get enough of, so much so that the board of directors promotes him to CEO and the world knows who he is. So get started and get your book out the door!