First, you'll need to connect your wallet by clicking "Connect wallet" in the top right corner. Next, click on your profile pill. You'll be redirected to your profile page. Click on Edit profile on the right.
Click "Sign message" to prove ownership on the wallet. Your wallet will prompt you in a modal, click Sign.
Once you've signed the message, you'll be taken to the "My account" page. Here, you'll be able to add a biography, a website link, and your twitter handle.
To update your profile picture, click on your avatar. A modal will open, letting you select a new avatar from the Ordinals that you own.
Once you're done making all your desired changes, click Save. Then click on your profile pill in the top right corner again to see your updated profile. You'll see your bio and links appear. You can always go back and edit your profile whenever you feel like it!