How to create an ERC721 NFT the best way in 5minutes (with smart contracts and metadata code)
So an NFT is simply a piece of information that lives on the blockchain, represented by a visual image. This is not a guide on how to design NFTs. For that you need to learn digital design with tools such as Illustrator and Photoshop.
Btw if you want to create your own NFT collection I wrote a massive guide to show you everything step by step from own experience launching collections here: https://merunas.gumroad.com/l/nft-guide