I have a little question

Hi. It's been awhile since I've been doing some coding. And I'm trying to find a specific script. I'm trying to find code or whatever that can make my page. With a few links staying in the same place. But the content changing only. For example on this site here: http://romeldris.ca When you click on "About" on the top left. The title of the blog stays the same but content changes. I'm looking for something like that. I'm not sure if i did it right on my test page. http://604-media.ca/indextest/. But I want to find that right code. Can someone please help me. Thanks.