Themes - Why cant I change my desktop themes that I downloaded from the internet??

Why cant I change my desktop themes that I downloaded from the internet??

I downloaded few themes from the internet and it is saved in my desktop as "compressed files". I am just not able to change my themes..I tried right clicking n then pressing the properties button and then i tried browsing for the file but those themes are not visible in the panel when I browse but it is clearly visible in my desktop as compressed files..what should i do??

Public Comments

well to put is simply "compressed files" are like just bunch of file compress/made smaller then "packed" into another format. you need something like winrar to "decompress" it. http://www.rarlab.com/download.htm
I assume you're having Win XP and zipped themes, right? Right-click compressed theme-file with mouse and select "Explore". Now you should see the content of the compressed file. Select the files inside compressed file (press Ctrl-A) and then Copy (Ctrl-C). Open "My Documents" folder and paste files in there. One of the files should have extension "theme". Check for the new theme in "Display Properties\Themes" dialog.
extract the file then browse for the image.
the 2nd person Timoj is right!