All you have to do is being in the group to qualify.
The giveaway's will be based on a Random generator so everyone have the same amount of chance to win something.

The giveaways are in-game (guild wars 2) items.

Remember the contest runs until December 30, after that a winner will be picked.
For more info, please check Best Wintersday Screenshot

Remember the contest runs until October 31, after that a winner will be picked.
For more info, please check:
Win a Permanent Black Lion Merchant Contract!

The winner of the contest will have their logo here on the steam group and get a Permanent Black Lion Merchant Contract[wiki.guildwars2.com]