didnt you give this example does this mean that when i will be setting a background in my friendster i must put this
background-image: url http://examplesite.com/bla/bla/bla
you must have brackets around the web address bit, e.g. url(http//www.somesite.com/yada/yada/yada)
although its possible you shouldn't use a web picture that isn't yours or under your control. First its stealing bandwidth from whoever is hosting the picture, second they could change it to anything the like at any time and your link would show the new picture. And that new picture could be offensive, rude, etc.