Navigate to Scopus, which can be found under "S" in "Find a Database". From here all you need to do is search for the article in which you are interested. To the right of the search results, you can see the number of times the article has been cited. You can also analyze whole journals by clicking on the "Analyze Journal" link above the search box and searching for a journal.
Navigate to Google Scholar, which can be found under "G" in "Find a Database". Here you simply search for the article in which you are interested. Under the link, you can see the number of times the article has been cited.
Please keep in mind that these methods may not produce a complete list of all times an article is cited because each searches different databases and sources.
