Um...I thought I am part of the community! If not, how do I become so? xD
To expand a bit on what Ian is saying, you are basically the new guy that comes into the group. So far, we've no idea who or what you may be. Instead of going "Hey guys, anyone have a smoke to spare?", you usually start with "Hello, I'm J and I hope I can be part of your group". The gog community is usually open minded and friendly, though there have been a few attempts to exploit it lately, thus we are a bit wary of newcomers.
Take a look through the forum, feel free to enter in the few giveaways that are usually running (xyem and Ian are hosting a weekly one each, though there may be a few requirements for entry), and feel free to express your opinion.
Be aware though that most people here are a bit older than the usual gaming forums, so as a rule of thumb assuming you are talking with someone who may have taught you a class at some point.
1 rep per day (or 12 hours) for posting, 5 rep for providing a solution to a question (thread marked as question), and up to a few points of reputation for a high rated post (while minus some points for a low rated one). Rep isn't anything significant, more or less how active you are in the forum.
Oh, and welcome to GOG.com, hope you enjoy your stay.