There are videos on hub balancing and it may also be in the DuBro instructions.How can you tell if it's at the hub? I have a Dubro balancer, not too familiar with the finer points of it...
Balance the props first on a vertical plain.
Then correct the hub balance if the prop favors a horizontal plain. As Steve Aikens said above, you can add nail polish to the lighter (upper) side of the hub to compensate.