That's all あなた have to do. Comment, post picks, maybe 提出する some リンク または pictures または something that people can and will be a ファン of. Make them different from the ones already 投稿されました though, または no one will bother to look at them. Keep at it and the medal will be your reward.
But あなた know, あなた really shouldn't be contributing just because あなた want a medal. あなた should be doing it because it's fun, and あなた want to. The メダル are supposed to be something that あなた just get along the way.
