Open a Web browser and navigate to one of several sites, such as Son of Citation Machine, KnightCite or APA Citation Wizards. These are all free and relatively easy to use.
Try several tools and select the one you prefer. Some tools work exclusively for online resources, while others are more versatile. KnightCite, for example, can produce citations for books and physical journal articles as well, provided you have the necessary information on hand.
Search for browser add-ons if your research will primarily take place in the virtual world. Zotero and Cite This! are two such add-ons that work with Mozilla Firefox to produce APA formatted citations of Web pages. Be sure you read the fine print and hardware requirements before installing third-party software onto your system.