I have been a member for a while but not really used it much yet - waiting on getting a phone with a camera that works! Think its all about photo sharing but you can annotate your photos with a short description. Don’t think you can tag your shop/website in comments but you can add it to your profile - I have seen comments on there with " link to shop in profile" on. I will be following this thread with interest as I want to know what its all about too!
BTW there are a couple of other threads on this subject which might help