The Cloth Bazaar is a map available on Nilly's Realm used for buying custom dyes and cloths for the player's characters. Dyes and cloths are one-time use consumables, and must be purchased each and every time a player wishes to apply the dye or cloth to a character.
Dyes and cloths come in two varieties: small and large, which apply the custom color or pattern to different areas of the character's current skin. Dyes cost 51 fame and cloths cost 160 fame. Keep in mind that on Nilly's Realm, some custom skins cannot be modified by dyes or cloths.
For more information about dyes and cloths, Realmeye has it covered.
A quick way to get to the bazaar is typing /bazaar into your chat. It will teleport you to the Cloth Bazaar.