It is generally a good idea to create a separate action that simply displays a page. For example, you really can't use the action submitCagetoryForm to display the ParameterSelection JSP because that action is expecting to process input from another form.
While it is possible to simply create a link to the JSP itself, it's not considered best practice. Best practice is to hide all of your JSPs behind an action. Besides, usually there is some type of processing necessary before displaying a page such as pre-populating values or filling options in drop-down boxes.
If there is no processing needed to display a page, you can use a "forward action mapping". This type of action mapping doesn't use an Action class, but just forwards to the JSP. Example: