Who is interested in that article you wrote?
Google Scholar will tell you some articles that have cited it. Citation databases like Web of Science or Scopus would tell you of some, too (a subscription is needed for both).
Other people might be interested too, but not cited it in their own published work. They might have blogged about it, or tweeted about it.
Altmetrics count mentions on Twitter, bookmarks in Mendeley and CiteULike, discussions on blogs, and provide a measure of usefulness that is complementary to counts of citations.
Some online journals and other sites will show you Altmetrics. There is also a bookmarklet you can install (Firefox, Chrome and Safari only) and then, when you are looking at a PubMed record or a journal article that has a DOI, you can see the Altmetrics.
I installed the bookmarklet, and using it on this BMJ article (an example taken from the Altmetrics site), I can see that it has been blogged about by 3 people, tweeted about by 111, and is on 10 Facebook pages. I can then click through to see which blogs, which people on Twitter, and see where in world they are. I can also see an overall “Altmetric Attention Score” which ranks the attention this article has received relative to other things of a similar age, and other things in the same journal.
If you have a connection to a University, you could also contact their Library for advice and more information.