1. Open your Metamask browser extension and click the icon in the top-left corner
2. Search for "Polygon Mainnet" and click Add, then approve the connection
3. Your wallet is now set up to use the Polygon network. Click the icon in the top-left corner again and switch back to the Ethereum network for now.
4. Get some Ethereum by copying your wallet address and sending ETH to it from another wallet or from an exchange like Coinbase or Gemini.
5. Go to https://app.1inch.io and swap Ethereum for Polygon
6. Switch back to the Polygon network in your wallet