When selling NFTs at a fixed price, it's important to know that you can cancel the listing at any time before a purchase is made.
Navigate to your profile page by clicking on the wallet icon situated on the left toolbar.
Clicking on the NFT you want to sell, will automatically add it to the smart cart titled “List”.
Open the cart. Enter the price you want to list your NFT at and the expiration date, and click List.
If this is your first time selling an item from this collection, Pixl will ask for you to approve the collection for trading. Click Approve. You only need to do this once per collection and only if the collection has not been approved for trading on OpenSea previously. Once you've approved a collection, you don't need to do it again, unless you revoke the approval later on.
Lastly, you'll need to confirm the listing by signing a signature in your wallet.