Guide to the Bazaar...

Buying

Buying and selling at the Bazaar is fairly simple. Go to Olde Town in Wizard City. The Bazaar is on the Right as you enter, in front of the NPC Gloria Krendall.  Once you are inside walk up to Elik Silverfist and press X. The store will open for you. Let the items load then check the box that says Usable on the bottom right. Now only the gear you are able to use is available to you and you can't buy anything that you can't use! It will show you the stats of the new gear compared to the stats of the gear you have equipped, this is helpful in making your purchase descisions, but don't buy the first thing you see that is better, keep looking, there could be something even better!.

You can buy more than just gear at the Bazaar. If you click the House with the yellow arrow behind it on the Top Right Corner, it will take you to housing items! You can buy things to decorate your dorm or house with now. (Houses become available at level 15, so save your gold!)  With housing items there are MANY thing you can buy in the bazaar that you can't buy anywhere else. However, there are also items that you can buy cheaper every where else. If you're a bargain hunter like me, go check the furniture shops before you buy from the bazaar, you'd be amazed how much gold you can save!  This is the best place to buy Garden seeds as well, though it's fairly easy to farm these as drops and you're backpack will eventually have more seeds than you can garden at one time.

If you click the same arrow again you will now be in Treasure Cards! And if you click again you're at Pet Snacks to use in training your pet, and Reagents for Crafting. 

You can buy everything but pets here. 

Selling

Click on the sell tab at the top of the window. The gear in your backpack is now accessible. CAREFULLY choose the items that you want to sell, I can't tell you how many times I've sold something only to have to buy it right back. Luckily they have fixed it so that you can't sell anything that you have equipped, but all other Auction-able items  in your backpack are available for sale. Click Sell, then it will ask if you are sure you want to sell the item, click yes. The gold will appear at the bottom of the page in your total.

You can also sell out of your bank from the bazaar, but be careful not to sell something you are saving.