[PhatboyNYC]

The site says
"This month we’ll select winners based on the quality of your contributions. This includes the start of a Windows Phone 7 related discussion that receives the most meaningful posts, the most valuable and insightful contribution to a discussion, as well as the most quality posts contributed overall. The better your contribution, the better your chance is to win one of these great prizes."

However, they don't specify a particular thread or forum on the site where to make posts/contributions.