Like the trade quests in Dailies and Guild (see: here and here) this Tutorial quest is also sticking.
The requirements:
- Buy at least 10 resources through trading with other players.
- Sell at least 10 resources through trading with other players.
The "buy" works fine, but the "sell" is being read by the game as "pay". If the new player offers 10 [whatever] and someone else buys it the quest ignores it. If the new player finds an offer for something that costs 10 [whatever] and buys that the quest completes.
Rather awkward in the tutorial levels.
Note for new players: Find something cheap, like Pine or Stone or Fish or ask in the Trade Tab for help. It's very likely someone will post something cheap to lend a hand.