So how do we beginners and normal folk go about this business? We treat it as a side-hustle. A little bit of work in transmog can go a long way down the track, but the key point is that it will take time for you to see the fruits of your labour. Make sure you have gold from other activities that can bankroll you, while your transmog business is built up. This can be professions, carry runs, current content farming for materials, whatever it is. In these early stages, DO NOT waste time making transmog your main source of income, especially if you need gold now or soon. Transmog early on is best treated as gold over time.
Once you download the addons from the website to the downloads folder, you can right-click on the compressed (zipped) addon folders, and select "extract all". After that, you go to Windows folder, click Program Files (x86), and scroll down until you see World of Warcraft. Then click on Interface, and then select "Addons". After that, select "extract all" to transfer unzipped addon files to that "addons" folder.
Most of the players make the mistake of only listing 30-50 transmog items on the auction house and then hoping to get half of them sold until the next day. Me and a lot of other gold farmers and transmog sellers do have 3.000-10.000 items on the auction house across various realms. It does not mean you have to do it that way – but if you have 1000 items listed, chances are higher you can sell up to 10 per day. With only 100 items listed, you have to be lucky to sell one. Of course, the sells are not guaranteed if you post more items. But i’m sure you have a lot more fun if you open your mailbox and 10-20 items are sold