NFT crypto is a token and is sold and purchased on crypto currency exchanges such as Binance. NFT Art is sold and purchased on platforms such as Opensea
This is where things get a little confusing, there is a crypto currency token with the name NFT that you can trade just like Bitcoin, ethereum, dodgecoin etc . In order to do this you need an account on a cryptocurrency exchange such as binance.
Once registered and verified one is able to trade the NFT crypto token. Buy low and sell high is the usual pattern for crypto trading.
On the other hand there is NFT Non-fungible token which has become the main topic of conversation in recent months. This is usually associated with some digital content like art or video files.
The most popular platform for NFT Art trading is Opensea marketplace and there are others coinbase has recently launched a NFT marketplace and Rarable is another one. These marketplaces allow customers to view the art and buy it using crypto currency such as ethereum or polygon and yes there are marketplaces for other blockhains like solana and Avalanche.
Selling NFT Crypto is different to selling NFT Art, for the crypto token you need the services of companies like Binance for NFT art look to places like Opensea.