If you go into your inventory from the main menu, and select an item- there will be an option to sell the item... just click that.. set your price, decide if people are buying single units or the entire set... confirm the process and you're all set.
If you want to change your selling price or cancel the selling of an item, just click the Bazaar option in your inventory and you can select what you ahve up.
As you've seen, if you've done it correctly, there will be a brown bag by your name~
Hope that helps!
Maverick Hawkeye. Kashuan.