How to set up company branding in Office 365?

Step 1: Sign into https://portal.azure.com or http://portal.office.com/ and click on Admin.

Step 2: Navigate to Azure Active Directory.

Step 3: In the Azure Active Directory admin center, click on Azure Active Directory on the left pane.

Step 4: Scroll down and click on company branding.

Step 5: Click on Configure on the top.

Step 6: Choose the company logo, text, etc., and click Save.

Step 7: You can open the custom login page by accessing https://login.microsoftonline.com/?whr=domainname.com