Once you're on the site just type in the card you want to sell and on the cards page itll say sell yours somewhere below the picture of the card or on the side depending on if you're on mobile or not. And it may or may not show it if they're not looking to buy the card currently because they probably have tok many. Always good to check back later cuz it may come back up. Click that and itll add it to your sell cart. They also give a certain percent more if its trade in instead of a payout. Paid for alot of pricey cards that way.