On your dashboard page, you can add a metric by clicking on the three dots at the top right and select "Add a metric":
You can also use the shortcut:
A window appears:
Select the data base where you want to pick a variable in the up menu,
Register the name, a description (not mandatory), the variable (mandatory).
You choose the function (by default it will be the one defined in the variable configuration) and the period.
The specification of color, conditions or events are not mandatory.
Click on the yellow button "Update a metric" at the bottom right to save it.
Tip: If you want to create a metric using a Date/Time variable, you have to create a calculated variable using Time Operators . Use this calculated variable to create your metric.