Nifty button image and position

Hello

How in .xml i can set image for my button? Also i got question about positioning. I got panel:

[java] <panel id=“logoPanel” height=“536” width=“728” backgroundImage=“Textures/GFX/Interface/GUI/tltBig.png” childLayout=“center” visibleToMouse=“true”>
</panel>[/java]

Its on center of screen but i also want to put that a bit higher.