A vendor area exists in every world, and are either in the center zone of the world, or very near it. Vendors offer many items up for sale, and you can browse through the shops at any time. They all sell or buy items for gold. If you would like to buy an item, walk up to the vendor and type "X.” Then, scroll through the available items to choose the one you want, customize its colors, and click BUY. Different color combinations have different prices, so experiment for the best look and bargain.