Google has good information on using Google Calendar on their support page.
You can do a one-time import of data from one calendar system into Google calendar, which would be good if you are switching from one calendar system to the other. (Say from UICalendar to Google calendar.) You can also subscribe the other calendar into your Google calendar; this gives you a connection that allows Google to update that calendar's data in your Google calendar on a regular basis. Sometimes subscriptions are read-only, but in some cases you can create a subscription that allows you to update the other calendar in Google calendar. Calendar subscriptions use iCal format.
There are levels of sharing, from just see your busy times to allowing the other person/device/program to add or modify entries; see Google's Calendar Sharing Options for Google Apps@UIC and other Google Calendar sharing options.
You can use your GoogleApps calendar on your smartphone in a few different ways, either through a program or through the web view. See Using GoogleApps@UIC Other Email Programs and Devices. You can also use Google's mobile webapp.
June 10, 2013