Ok, I had a look at your other post. Mondoman suggested that you were probably a student and this was a project set for you. I'm guessing that he was right as you are still asking. For anyone else this was Serendipity's other post;
http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&t=199958&highlight=
Lets start with the basics then, UV is Ultra Violet light and is part of the electromagnetic spectrum along with visible light (the light we can see). UV light is given off by the sun which is what you want to detect with your outdoor UV monitor, unless you have another reason for monitoring UV light for sports. Anyway just search UV in wikipedia and although it will take a while to read that way you might actually understand it.