NFT marketplace is just like any other bazaar where goods are brought for sale, a place where buyers meet sellers to trade the NFT wares if they come on accepting terms on prices. The buyers can buy the NFTs in form of tokens that were pre-set by the sellers or they can bid them as per their price in the digital auction. Smart contracts facilitate trade with transaction protocols.
Just like we have different markets for different goods we have different NFT Market spaces for different wares. Digital art, NFT art buy signatured artifacts of celebrities, game collectibles, trading cards are highly traded NFTS.

Similar to any market space purchase we do in our domestic life, purchasing tokens in NFT Marketplace has similar steps in 
marketplace and marketspace
1) Signing up on an NFT platform
A few of the best platforms in their niches are Binance, OpenSea, Axie, Crypto.com, Magic Eden, Nifty Gateway, Rarible.

2) Selecting a digital wallet 
A few of the best digital wallets are Metamask, coinbase, Alpha wallet, Enjin Wallet, Trust wallet, Math wallet, coinomi.

3) Browse your listings from items that are sold at a fixed price and also the items that you would bid them in the digital auction from the most expensive NFT to least expensive NFT

4) Buy the listings if you are purchasing at the fixed price and bid on the listings in auctions.
5) Once you are out-bid you will be notified.  For those items that are purchased, you will receive a receipt of the transaction of purchase.

Major NFT marketplace offerings are:

1. NFT for Music
2. NFT for Art
3. NFT for Video
4. NFT for Games
5. NFT for Sports
6. NFT for Fantasy Sports
7. NFT for Accessories
8. NFT for Real Estate
9. NFT for Infrastructure Developments
10. NFT for Domain Names