Why did you start a new topic when people have already offered help
in your previous topic?
Since you are new to Struts 2,
you should probably start with some general tutorials so you understand how Struts works.
This tutorial is a good one to start with. Only after getting a detailed understanding of Struts, would I throw AJAX into the mix. There's a lot of moving parts in a web application and you have to have them all lined up correctly to get them to work. The more examples you look at, the better off you'll be.
Once you have the basics down, I mentioned the Struts 2 jQuery plugin in your previous topic. It makes jQuery (which is already pretty easy) even easier. Have a look at the examples
here and they may help.