To sell an NFT first you will have to create one. You can do this simply by clicking on the Connect Wallet button on main page and follow by setting up your profile in the My Profile and afterwhich heading to My Collections to mint an Collection of NFTs of your choice, following the on page instructions which includes selecting the file and inputting the details of it, After uploading is successful, you will be redirected to your item detail page where you can set the item for sale or auction, or head to My NFTs in profile Settings.