Visit office.com on your computer and click Sign in.

This is the starting point for the whole setup. Begin on the Microsoft 365 website in your browser.

Open your web browser on your computer.
Go to office.com.
Look for the black Sign in button.
Click Sign in to begin.
Computer screen
Office.com homepage with the Sign in button visible
What to look for

You should see the Microsoft 365 page with a clear Sign in button near the left side of the screen.