Windows 8.1 Tile XML

Hello,

I hope this is the right place to ask this seeing as I'm not a developer. I'm trying to customize the tiles on my start screen, and a how to page from the Microsoft dev center tells me how to do so using xml. I followed the directions carefully only to see that there was no change. I worked with the "snipping tool" trying to keep everything the same (size, text color image etc.) but change the color from red to purple. Here's the exact code I entered into the xml document:

<?xml version="1.0" encoding="UTF-8"?><Application xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><VisualElements
        BackgroundColor="purple"
        ShowNameOnSquare150x150Logo="on"
        ForegroundText="light"/></Application>

 Am I completely missing the point of all this? It says that I should have some knowledge of xml, but alas I have none, so if this needs a lot of work don't bother. Any helpful links or pointers would be appreciated though.

Thanks :)