Reddit does not allow its users to monetize sub-reddits and earn money from it directly. You should not put ads on your sub-reddit because if you do so, you might get banned immediately. You can only leverage Reddit to boost your own business by participating in the communities.
What does -1 karma mean? It doesn't do anything, they're just internet points. Reddit calls the collection of upvotes and downvotes a user receives karma. You... more