Different events are colour coordinated, according to which type of event they are. If there is a green icon on your calendar, this indicates a holiday. If there is a black icon, this indicates a general event. To create your event, go to:

Menu > Collaboration > Event Creation

• Enter the applicable details for your event and click Create.
• Select the class and department as you wish, ensuring you save both and then click confirm

For more information, watch this timestamped video: