If you're a new QuickBooks user, the dashboard content will be empty. This page will be updated once you start entering transactions. To do that, you can use the + New button on the left panel and select the transaction you want to create.
Please see this sample screenshot for a visual reference:
Once done, your dashboard will display the real-time overview of your company finances.
You can always reply to this thread in case you have other concerns with QuickBooks Online. I'll be around to help you out some more. Have a great day!
The Dashboard is already set to display shortcuts and an overview of your business and customizing it is unavailable. You can only customize the reporting period of the report tiles.