Your First Smart Contract

1Install MetaMask

1. Go to metamask.io
2. Click Download and add to browser
3. Create new wallet
4. SAVE YOUR SEED PHRASE!

2Get Test ETH

1. Open MetaMask, switch to Sepolia test network
2. Copy your wallet address
3. Go to sepoliafaucet.com
4. Paste address and request ETH
5. Wait 1-2 minutes

3Open Remix IDE

1. Go to remix.ethereum.org
2. In file explorer, click contracts folder
3. Create new file: HelloWorld.sol

4Write Your Contract

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

contract HelloWorld {
    string public greeting;

    event GreetingChanged(string oldGreeting, string newGreeting);

    constructor(string memory _greeting) {
        greeting = _greeting;
    }

    function getGreeting() public view returns (string memory) {
        return greeting;
    }

    function setGreeting(string memory _newGreeting) public {
        string memory old = greeting;
        greeting = _newGreeting;
        emit GreetingChanged(old, _newGreeting);
    }
}

5Compile

1. Click Solidity Compiler icon (left sidebar)
2. Select compiler: 0.8.20
3. Click Compile HelloWorld.sol
4. Green checkmark = success!

6Deploy

1. Click Deploy & Run icon
2. Environment: Injected Provider - MetaMask
3. Connect MetaMask when prompted
4. Enter greeting: "Hello, Blockchain!"
5. Click Deploy
6. Confirm in MetaMask
7. Save your contract address!

7Interact

• Read (free): Click greeting or getGreeting
• Write (costs gas): Enter new message in setGreeting, click transact

8View on Etherscan

1. Go to sepolia.etherscan.io
2. Paste your contract address
3. See your contract and transactions!