Hi there and thank you for your feedback, so there are two ways to go about putting your NFT for sale. 1/1s you cannot put on sale, you can only put on sale Limited or Open Editions.

For Limited or Open Editions, you can create an NFT by using the "Create" button on the NFT's tab. After creating the NFT, you will have a pop up which will suggest you add it to a mint page. If you do not select this mint page, you will need to go back to your NFTs tab, select "Limited" or "Open" edition as a filter, click the tertiary menu, and click "Create Mint Page".

From there you can setup your mint page and put it on sale. Let me know if you have any other questions!