Need help with html and css

[DeNeDe17]

Hello ..
i found a small css tmeplate on the internet and i like it ...
but i want to make something different ...
so ...
here is a picture of the template
http://i39.tinypic.com/24bku4g.png
i will change the name and the menu ... etc..
but what i want to do is .....
when i click somthing from the menu or from the left side menu i want that the content to appear in the same page but in center ..
different frame .. as i searched on the internet i've found that this si the name ..
http://i40.tinypic.com/ndx8w2.png

if u need the files ... here they are ..i've attached them ..
thank you :)

[Slickerey]

Do you want it to replace what's already in the center or do you want it to pop up in a flash window?

[DeNeDe17]

i want to replace what's in center with content of my own ..
of course with external files ...
but when i click a button from menu i want the content from my external file to appear in the middle