The publisher has put your story in print, but it is still your job to sell it!
Not what you wanted to hear, I know.
How much better it is though to understand the reality of the business of books.
The only magic behind the business of moving your books is marketing and that's up to you.
Here are three specific things you can do online:
1. Create a platform - set up a website / blog / Face Book page/ You Tube your book trailer and link them.
2. Buy/ secure as many versions of your name as a brand and the title(s) of your book(s) and direct them to your site. Google your name and book title to investigate how easy or not it is to find you online - taking the above action helps.
3. Be sure to have a media section on your site - basically what other people say about you. Collect quotes, reviews, comments, news articles, TV appearances and so on. And be sure to mention in every interview and article not only how fans can find you online - but use the word "book" and its title often so people are reminded that there's a book to buy!
And it goes without saying, make sure you are real and sincere when you present yourself - It is much easier to sustain over time than to upkeep an image.
Above all, happy writing!
Can you say what your book is about in one sentence?
Work on it!