You mean the background color?
You can do that with JavaScript. And you would include that in a link I guess:
<a href="#" onclick="document.bgColor='green'; return flase;">link</a>
bgColor? Were you born in a barn? ;)
At least give the guy something from this century (and typed correctly). ;)
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OP, you can use CSS to set a different default background colour for your page(s).
http://www.w3schools.com/css/default.asp
http://www.w3schools.com/css/css_reference.asp#background
http://www.w3schools.com/css/css_background.asp
If you want to dynamically change it from one colour to another, then you can use javascript…
… onclick="document.getElementsByTagName('body')[0].style.backgroundColor='green'; return false;"…
For something more permanent, take a look at javascript styleswitchers (http://www.google.com/search?q=javascript+styleswitcher) and php styleswitchers (http://www.google.com/search?q=php+styleswitcher)