Opening the MetaMask extension is a simple and quick process. Once you have added the extension to your browser, look for the puzzle piece icon on the top right corner of your Chrome window. Click on it to see all your installed extensions.

You will find the MetaMask logo among them. Click on it, and a small window will pop up with the option to either log in if you already have an account or create a new one if you're using MetaMask for the first time.

Once logged in, you'll be able to access all the features of your MetaMask extension wallet directly from this window. From managing your Ethereum assets to interacting with decentralized applications (dApps), everything can be done conveniently within this interface.

Make sure to keep your login information secure and remember that anyone with access to your browser can potentially access your wallet as well.