After installing the extension, press the Metamask icon at the top right of your screen

and you will see the following screen:

and you will click on: Continue

Then you must create a password (secure) and click on: Create

You continue by clicking next, you read and accept the terms of use.

Click on Reveal secret words.

You will see a phrase that contains 12 words, which you must save in a safe place and press next

You must verify the phrase generated previously, at the end click on confirm.

Congratulations, You have successfully created your MetaMask account.