Adding NFT Metadata and Images

Step 1: Upload Your Image to IPFS

You need a place to host your image so it can’t be deleted. Pinata is the easiest free tool for this.

1. Go to Pinata.cloud and create a free account.
2. Click Add Files -> File and upload your NFT image (e.g., `my-cool-art.png`).
3. Once uploaded, Pinata will give you a CID (Content Identifier). It looks like a long string of random letters and numbers.
4. Copy that CID. Your image’s IPFS link is now: https://ipfs.io/ipfs/YOUR_IMAGE_CID

Step 2: Create the Metadata JSON File

NFT marketplaces (like OpenSea) look for a specific JSON format to read your image, name, and description.

1. Open a simple text editor (like Notepad or VS Code).
2. Paste the following JSON format and customize it:

{
  "name": "My Epic Testnet NFT",
  "description": "This is my very first NFT with an image!",
  "image": "https://ipfs.io/ipfs/YOUR_IMAGE_CID",
}

3. Save this file on your computer as `metadata.json`.

Step 3: Upload the JSON to IPFS

1. Go back to Pinata.
2. Upload your `metadata.json` file exactly like you did the image.
3. Pinata will give you a new CID for this JSON file.
4. Copy this new CID. The link to your metadata is https://ipfs.io/ipfs/YOUR_JSON_CID

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Step 4: Update Your Smart Contract in Remix

To allow your contract to store these URIs, you need to use an OpenZeppelin extension called `ERC721URIStorage`.

Go back to Remix and update your code to look like this:

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

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/access/Ownable.sol";

// Inherit from ERC721URIStorage instead of standard ERC721
contract MyNFT is ERC721URIStorage, Ownable {
    uint256 private _nextTokenId;

    constructor() ERC721("MyTestNFT", "MTNFT") Ownable(msg.sender) {}

    // We updated safeMint to require a 'uri' when minting
    function safeMint(address to, string memory uri) public onlyOwner {
        uint256 tokenId = _nextTokenId++;
        _safeMint(to, tokenId);

        // This links the specific token ID to your JSON metadata on IPFS
        _setTokenURI(tokenId, uri);
    }
}

Step 5: Deploy and Mint

1. Re-compile and deploy this new contract in Remix exactly as you did before.
2. Once deployed, open up the contract functions in the bottom left.
3. Find the `safeMint` function. You will now see two boxes:

• to: Enter your wallet address.
• url: Paste your JSON IPFS link here (e.g., https://ipfs.io/ipfs/YOUR_JSON_CID).

4. Click transact and confirm in MetaMask.

Once the transaction goes through, your testnet NFT will officially have a name, description, and image tied to it! If you go to a testnet marketplace like Testnets OpenSea and connect your wallet, your image will show up.