Firstly, we need to create a new mint account for the NFT we want to mint and an associated token account for owning it. 
var mint = new Account();
var associatedTokenAccount = AssociatedTokenAccountProgram
    .DeriveAssociatedTokenAccount(Web3.Account, mint.PublicKey);
Secondly, let’s define the metadata of the NFT. 
var metadata = new Metadata()
{
    name = "Test",
    symbol = "TST",
    uri = "https://y5fi7acw5f5r4gu6ixcsnxs6bhceujz4ijihcebjly3zv3lcoqkq.arweave.net/x0qPgFbpex4ankXFJt5eCcRKJzxCUHEQKV43mu1idBU",
    sellerFeeBasisPoints = 0,
    creators = new List<Creator> { new(Web3.Account.PublicKey, 100, true)}
};
We can now construct the transaction, whichi consists of 5 istructions:
  • Creating the Mint Account
  • Initilizing the Mint Account
  • Creattin the AssociatedTokenAccount
  • Minting the NFT
  • Creating the Metadata Account
  • Creating the Master Edition
var transaction = new TransactionBuilder()
    .SetRecentBlockHash(blockHash)
    .SetFeePayer(Web3.Account)
    .AddInstruction(
        SystemProgram.CreateAccount(
            Web3.Account,
            mint.PublicKey,
            minimumRent.Result,
            TokenProgram.MintAccountDataSize,
            TokenProgram.ProgramIdKey))
    .AddInstruction(
        TokenProgram.InitializeMint(
            mint.PublicKey,
            0,
            Web3.Account,
            Web3.Account))
    .AddInstruction(
        AssociatedTokenAccountProgram.CreateAssociatedTokenAccount(
            Web3.Account,
            Web3.Account,
            mint.PublicKey))
    .AddInstruction(
        TokenProgram.MintTo(
            mint.PublicKey,
            associatedTokenAccount,
            1,
            Web3.Account))
    .AddInstruction(MetadataProgram.CreateMetadataAccount(
        PDALookup.FindMetadataPDA(mint),
        mint.PublicKey,
        Web3.Account,
        Web3.Account,
        Web3.Account.PublicKey,
        metadata,
        TokenStandard.NonFungible,
        true,
        true,
        null,
        metadataVersion: MetadataVersion.V3))
    .AddInstruction(MetadataProgram.CreateMasterEdition(
        maxSupply: null,
        masterEditionKey: PDALookup.FindMasterEditionPDA(mint),
        mintKey: mint,
        updateAuthorityKey: Web3.Account,
        mintAuthority: Web3.Account,
        payer: Web3.Account,
        metadataKey: PDALookup.FindMetadataPDA(mint),
        version: CreateMasterEditionVersion.V3
    )
);
Finally, let’s sign and send the transaction: 
var tx = Transaction.Deserialize(transaction.Build(new List<Account> {Web3.Account, mint}));
var res = await Web3.Wallet.SignAndSendTransaction(tx);
Debug.Log(res.Result);
The console will print the transaction signature, which you can investigate in the inspector and should looks similar to this transaction, You can lookup the mint address in the explorer, which should be similar to this NFT