Any Element can be turned into an Event (placed onto a Calendar) using the Event Dates Field Type.
To begin placing events on your calendars, simply add an Event Dates field to your element.
In the field settings, you will specify which calendar should contain the events edited by this field.
You can add multiple Event Dates fields in a layout, if you want one element to represent events on multiple calendars (or even multiple types of events on a single calendar).
Using fields in templates
When you invoke an Event Dates field in your templates, it returns an EventCriteriaModel pre-filtered according to the element ID and field ID.
For example, if
entry represents an EntryModel with ID 42, and
myEventDates is an EventDates field in the entry's layout, then...
...would return the same EventCriteriaModel as...