Setting new skin to default style:
once xml file is uploaded goto:
admincp>>vbulletin Options>>vbulletin Options>>Style & Language Settings
scroll down to the Default Style section (second option) there you will see a dropdown menu choose your new style then scroll down to the bottom and press "save"
refresh your browser and you will now see your new style up and running!
Note: this is original posted by HoxxyAll cridit goas to Hoxxy