Citing references are articles that include the article you are looking at in their references. So usually these are going to be related articles that are even more recent that the original article. They can help you move forward in the research process to see where the research is headed.
Citing references can also indicate if an article particularly important or controversal. If an article has many citing references, especially if it's a recent article, someone is talking about it. Most likely this is because the article is very good or very bad. Peruse the citing references to determine which is the case.
To receive most search alerts and access other advanced functions in a database, you'll need to create a free personal account. It's often a good idea to create a free personal account for databases you use most often so that you can take advantage of extra features, like alerts, saving citations, and more.
Look in the upper right corner of most databases to create a personal account.
In EBSCO Databases:
In ProQuest Databases:
In Web of Science:
Most databases will allow you to create alerts based your searches. You can get updated results through an email or an RSS feed.
Look near the top of your result lists for links to create search alerts:
Most online journals allow you to subscribe to their latest articles and/or table of contents through an RSS feed or email. Below are links to alert feeds for a number of journal providers in the sciences.