Use the Quick Search Box (QSB) to add a new event in the calendar.

Describe a new event by typing something like "Sat 9pm to 23.30 party time at my place" to create a new event on the next saturday from 9 to 11:30 pm with the subject set to "party time" and the location set to "my place".

Search Calendar will show one suggestion for each calendar below the search box. Selecting a suggestion will save it to the appropriate calendar.

It takes a little practice to get used to the input format.