(This feature is still in development.)
For now, early in Open Beta, any clothing you purchase in the Marketplace will be sent directly to your Dressing Room.
With Update 3 (December), you will now see a Warehouse button on the Action Bar. This button allows you to retrieve and store furnishings in a home you own. Furnishings are either the default pieces of furniture available in a home or additional pieces available for purchase in the website beta Marketplace. Owned clothing is still sent directly to the "Dressing Room" armoire, including the default armoire in the terraced homes.
See the Knowledge Base Article for "Decorating your own home" for more details on how to use the Warehouse when re-decorating.