In Backpack, you can have different calendars within your master calendar. These calendars are useful for grouping events by category or person. You might have calendars labelled "Sarah," "Jeff," or "Juan" for each one of those people. Or "business," "personal," or "travel" for those categories. Each of these calendars can have a different color also. Events will then show up in that color.
To choose the Calendar you want, click the "Calendar" link at the top of every screen.
Then click the "Add a calendar" link in the right sidebar.
Name the calendar, choose its color, and choose who can view it.
Now add an event and select the calendar you want from the calendar pulldown.
Related: Backpack Calendar FAQs.