Making an NFT is easy. You can make one on your PC rn. Go to open sea. Open sea is a market place for NFTs. You need to create a metamask wallet and link it to a chrome add on. Once you do that go back to the open sea webpage and press the create page. It will ask you to confirm the link to your wallet and you will let it. Then you upload the file you want to make an NFT. You will fill out the details and description and how many copies there will be. Usually you need to pay to publish the NFT, but to avoid that, there's an option that will say "publish to" you will set this to the polygon blockchain. Then publish it and put it up for sale if you want. If you don't understand even one of the terms I mentioned, study before rushing.