And I have one another question.
In ton how nft marketplace contract works?
I think for any listing contract have to update or user create a new contract. Am I right?

They just read all user's transactions and try to find an NFT contract, as I know. Btw, if you deploy your own nft in testnet, you can find it in testnet.getgems.io

Do you have any working nft marketplace contract code?
I wanna write nft marketplace contract for myself

I will provide you an example of working contract, try to explore how does it work by yourself:

https://testnet.tonviewer.com/kQByDqUjb1orPTfqjPpxRro2lBmsZTSQSp7BCXVwiTMn491k

https://testnet.getgems.io/nft/EQByDqUjb1orPTfqjPpxRro2lBmsZTSQSp7BCXVwiTMn42bu

Thanks bro
I will do it

And what about marketplace (as like as getgems)
I wanna write my own marketplace contract to sell nft in fixed price
Does it exists something like this on GitHub?

Note that this is semi-chain contract and metadata is stored in blockchain. But you can also create an offchain contract with metadata stored in the internet

https://github.com/getgems-io/nft-contracts

I am familiar with this bro
I am ethereum developer and just new in ton