Gander is where you can trade other players. To this you click on Trade link under Location Actions and request a trade or accept a trade request.
Once in a trade you add the items you are trading to the other person and click on propose trade. once the other player has proposed as well it will show what both you and the other player are proposing to trade.Click on the Confirm link to complete the trade.
The Bazaar is where you can sell your items, there is also a 5% sales commission fee.
Gander is also the first mining location. From level 1 you will need to equip a copper pickaxe to mine copper ore. Once you make it to level 10 you can upgrade to an iron pickaxe and start mining iron ore.