All the information for configuring the calendar widget can be found in the app store under the tab configuration.
This might help you get started: https://www.mendix.com/blog/the-calendar-widget-easy-and-rapid-use-apaas/
I'm wondering if you ever managed to create the simple calendar app. I too am trying and even though the documentation is clearly written I am quite lost. The example calendar app from github is way too complicated - If I could understand that, I wouldn't be asking for assistance. Is there a tutorial somewhere on what is required (entities-attributes, associations...) to begin this "simple" project?
Here is a simple example of usage of the Calendar widget.
This entity contains the attributes needed for the calendar:
In the Datasource tab, enter the following:
note: the XPath Constraint is:
[AppointmentType = 'Vacation' and Schedule.Appointments_MainEmployee/Employees.Employee/Employees.Employee_EmployeeStatus/Employees.EmployeeStatus/Name = 'Active']
The first clause retrieves only Vacation items and the second clause ensures that we see only Active employees.
On the Event Data tab, enter the following:
That is (about) as simple an example as you'll see for the Calendar widget. One entity, retrieving Vacation events to display on the calendar.
Beyond that, there are many (many) configuration options and display capabilities, but that should get you started.
Hope that helps,