First you must have a Crypto Wallet (Ethereum Mainnet) and an NFT in the Opensea Market in order to use your NFT as an avatar.
1. Go to My Avatar by clicking on your current avatar.
2. Select NFT and a WalletConnect pop up will appear.
3. Click Connect Wallet in order to connect your wallet via QR Code or wallet application.
4. After connecting your wallet, you will need to input your desired NFT's contact address and Token ID (you can find these info be searching for your NFT on OpenSea)
5. Your NFT image should be displayed for you to resize and confirm as your avatar.