With Google Calendar, you can schedule meetings and events with your coworkers, just as in your old calendar application. Here's a selection of resources for learning about your new calendar.
Getting Started

Scheduling and other calendar basics  Schedule events, send invitations, add attachments, and print your calendar.
Set up reminders, sharing, and more  Set up event reminders, invitation replies, calendar sharing, and additional calendars.

Copy over existing events from your old Lotus Notes calendar.

Making the Switch

What's not available in Google Calendar  Most features you're used to in your old calendar are available in Google Calendar, but here are a few that aren't.
Tips and Tricks

Explore recommended Google Labs 
Enable year view, calendar attachments, world clock, and other enhancements to Google Calendar.

For even more information about using Google Calendar, check out the Calendar Help Center.