Moving data from a form to a portlet should be relatively straight forward.
Look at the following form that might make up the landing page of a portlet (the field is not namespace encoded, although it should be:
On the portlet side, you can simply pull out the field using the portetRequest:
Now this is an overly simple example, which excludes namespace encoding, not to mention the action processing phase of a portlet, where form handling should be performed. But it is simple, and it works.
Start with the simple, and move on.
Here is a link to the page where you can download the completed war file for this JSR-168 portlet application. It's been tested on both JetSpeed2 and WebSphere Portal Server:
There are also tutorials on that site that demonstrate some of the more advanced and complicated aspects of portlet development, including the creation of the JSR-168 Struts portlet, and JSR-168 JSF portlet, both of which use the Apache bridge, and both of which handle form input from the user.