Gaggle mail login facebook

I think you meant to ask about "Gmail" login, not "gaggle" mail login.

To log in to your Gmail account on Facebook, you can follow these steps:

1. Open Facebook and navigate to the top right corner of the page.
2. Click on the "Account" dropdown menu and select "Settings".
3. Scroll down to the "Security" section and click on "Apps and Websites".
4. Click on the "Add New App" button.
5. Enter the name of the app you want to add (in this case, Gmail).
6. Click on the "Add App" button.
7. You will be redirected to the Gmail login page. Enter your Gmail username and password to log in.
8. Once you're logged in, you'll be asked to grant permission for Facebook to access your Gmail account. Click on the "Allow" button to grant permission.
9. You'll be redirected back to Facebook, and you'll see a confirmation message indicating that you've successfully linked your Gmail account to Facebook.

Note that linking your Gmail account to Facebook allows Facebook to access your Gmail emails, contacts, and other data. Make sure you're comfortable with this before granting permission.