```csharp
var web3 = new Web3("https://mainnet.infura.io/v3/YOUR_INFURA_PROJECT_ID");
```
使用Web3对象,您可以查询余额、发送交易等。发送交易的代码如下:
```csharp
var transactionInput = new TransactionInput
{
From = fromAddress,
To = toAddress,
Value = new HexBigInteger(Web3.Convert.ToWei(amount)),
Gas = new HexBigInteger(21000),
GasPrice = new HexBigInteger(Web3.Convert.ToWei(20, UnitConversion.EthUnit.Gwei)),
};
var transactionHash = await web3.Eth.Transactions.SendTransaction.SendRequestAsync(transactionInput);
```