In Power BI service you can set a dashboard as featured, each time you login into Power BI service, it opens with that dashboard displayed.
If you don’t know how to create a dashboard, refer this : Create a Power BI Dashboard from Report
Set a dashboard as featured
Step-1: Open the dashboard that you want to set as featured & click to “set as featured “ icon.

featured Dashboard
Step-2: Confirm you want to set that dashboard as a featured dashboard.

Set Featured Dashboard
Step-3: Featured dashboard has been set successfully.

Success Message
Step-4: To see the featured dashboard re-login to Power BI service, it will show you featured dashboard just after login.
And if you don’t want re-login right now then click to “Power BI” in top header it will navigate to you featured dashboard.

Featured Dashboard 1
How to Disable featured dashboard?
To remove or disable featured dashboard just click to “Disable featured” link.

Disable featured
Note: You can set only one featured dashboard at a time.