Add your extras (cards you have to trade) the same way you added the cards on your wantlist.
I have also matched with a few cards that you have on your wantlist. Once you get a trade list added, trades will happen. Eventually, someone will walk you through your first one with the Trade Manager (just like they did for me!)
I post videos on YouTube of my trades and my collection, busting packs, etc. Take a look and leave some feedback!
https://youtube.com/user/brodiescomics
https://leagueofcomicgeeks.com/profile/brodiescomics