First, you download the dota 2 workshop tool, then subscribe to the addon. Then after you go in game, you will see "Custome Games" in play tab. Then you click on the drop down on the top, there will be "Subscribed Game Mode" and select "Dota Wardrobe" from there. After you loaded into the game, you will see a button on the topleft saying "Toggle cosmetic control panel on/off". After you click on it, you will see the panel as shown in the screenshot.

The main feature of the panel will be cosmetic swapping. Select current cosmetic slot from Current tab and see all available cosmetic to choose in Available tab. By pressing Replace, cosmetic in available cosmetic will replace the one from Current tab. Hopefully this helps :)

when i create a lobby it just stays on the loading screen please help

the first time you launch the map, it can take more than 10 minutes to load due to the amount of cosmetics the map has to load. After the first launch, it should be under 1 minute.

I don't really understand your instructions. By "Dota 2 workshop tools", you mean the Dota 2 Reborn beta, right? Then clicking the Custom Games tab, Library and Dota Wardrobe. From there, if I press Play Dota 2 Wardrobe or Create Custom Lobby, when I start it, I wait several minutes for the loading but then it just crashes.
It crashes every time without me doing anything. Am I doing something wrong?