I would like to suggest either adding a new Auction House NPC inside the auction house or use the auctioneer outside of the auction house to give a good description of how auctions work.
One of the most common questions new players ask is, "How do I do auctions?" It takes a lot of explanation for them to understand this. Hence why I think it would be best for them to be able to walk up to an NPC and read it.
The NPC could say something like this.
"Welcome to the Auction House!. Auctions will start when the timer at the front desk runs down to 0 minutes and the start of auctions will be announced! There are three auction rooms: Red, Blue and Green. To participate in the auctions you must bid by tapping the notice sign that says "Tap here to place a bid" You will only bid in small increments. The bidding for each auctioned item will end after a certain period of time and whoever bid last on the item will pay for the item and receive the item."