How to get site to automatically scale based on user's browser window

How to get site to automatically scale based on user's browser window

I am using Dreamweaver CS4 and I need to alter the site so that the
background automatically scales. I do not want to use a repeated
background (because this particular background does not repeat nicely)
then float the body over that, but would rather the entire site
automatically scale based on the users browser window.
Example I like: http://www.150-jahre-geze.de/150.html?no_cache=1
I do like this full screen page I do like other full screen pages, but we
don't have the photography or graphics to support this concept at this
point. How do I do this without a slider? Thank you for your help. I have
tried all I can think of and find at this point, but think I must be
phrasing my question wrong since I don't get any answers.