In case you want to make your Facebook group look more attractive by adding your very own Banner its very much possible now thanks to the tons of Facebook updates.
1. Login to your Facebok account.
2. Go to your Facebook Group (where you are a moderator, admin or creator).
3. Simply take your mouse to the top right corner.
4. You will see an option popup to add your own Facebook Group banner.
5. Just upload your own banner
And you are all set. this is a very simple trick yet many people especially Facebook Group moderators are not aware of it.