To enter the contest, you download a free app called 'Trampkomania with Windows Phone,' which is used to submit a picture of your personalized start screen. The contest starts today and runs through June 30th. 18 winners will be selected each day. Those who enter will have their start screen judged by "creativity, originality, aesthetic and the ability to use Windows Phone in the reported projects." Winners will be notified on the app.
source: Plus.pl (translated)