This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
You "call" an action class by specifying action="/myAction" in an html:form tag. This causes the Struts ActionServlet to call the action class when the form is submitted. If you're trying to call a class from the browser without submitting a form, that's called AJAX, and is something you'll have to spend some time learning about if you want to do it.