Adding NFTs in the browser version of the wallet:

Update your browser to the latest version and enable auto-detection of tokens in the security and privacy settings of the wallet, or reinstall the MetaMask plugin to enable adding NFT in the browser version of the wallet.

Make sure that the secret phrase is written correctly before removal.

Go to the NFT section of the wallet, and click "Import NFTs".

In the first line, enter the address of the NFT smart contract (in this example we'll use the Cosmic FOMO NFT Address): 0x587cBe061e96a425a60a637f430C2b20e6dA7A86, and in the second line the ID of your NFT, then click "Add".

Done! The NFT is added to your wallet.