NB: Dashboards and Rules (to trigger Alerts) require Devices (or Assets) with decoded data (measurements). You won't be able to configure dashboard WIDGETS, a RULE (or a Smart Device), if no device is available with correctly decoded payloads.
Go to the (Device) Dashboard module.
Devices Manager > Dashboard
Then:
From the top/right area, click on the “gear” icon and select “Add Dashboard”
Enter a name and press “Confirm”
Then from the top/righ area, click on the gear icon and select “Add Widget”
Confirm the default widget (Line Chart) and press “Save”
Now define the Measure that you want to visualize in the chart
Add a label (ex: “Temperature”)
Choose one of your devices (Object)
Select the input (one of the availables Measures known for this device)
Press “+”
Press “Confirm”
You have just built your first Dashboard, with one widget (a line chart) showing one measure for TODAY !
For more information: Dashboard (devices) Module