Open the Google calendar associated with your Google account. If you have not created a shortcut to access your calendar, type "calendar.google.com" in your browser's address bar and press the Enter key.
On the bottom portion of the Calendar sidebar, click "+" to the right of the words "Other calendars" to display a menu.
On that menu, choose "Create new calendar".
The Settings page for the new calendar will be displayed.
Enter a name for your secondary calendar and click Create calendar.
A gray banner at the bottom of the page will indicate that the new calendar is being created.
After the banner disappears from the page, click the arrow to the left of Settings at the top of the page to return to the list of your calendars.
The secondary calendar will appear in the list of calendars on the left side of the page. The new calendar will now appear in the dropdown list of Calendars to which you can post calculated events.