To set it up to not sync automatically, Connect it to your computer and in iTunes click the Summary tab. Then un-check “Automatically Sync when this iPhone is connected.” This stops iTunes from coming up when you connect iPhone. You can still start a sync manually.
To Set it up to not sync for all iPhones in iTunes choose iTunes then Preferences (on a Mac) or Edit then Preferences (on a PC), then un-check “Disable automatic syncing for all iPhones.” If this checkbox is selected, iPhone won’t sync automatically, even if “Automatically sync”is selected in the Summary pane
Go back to iTunes settings, make sure it is set to sync calendars.
Connect your iPhone to your computer. Updating will begin automatically.
To add manually: Tap and enter event information.Then tap Done. You can enter any of these: Title, Location, Starting and ending times (or turn on All-day) Repeat times—none, or every day, week, two weeks, month, or year Alert time—from five minutes to two days before the event If you set an alert time, iPhone gives you the option to set a second alert time, in case you screw up and miss the first one. When the alert goes off, iPhone plays a sound (if it is set on ring) and displays a reminder message.
Here is a good trick for Mac and PC users. The answer: Spanning Sync. Spanning Sync is a really cool utility that syncs iCal calendars with Google Calendar. Not one-way syncing, either — Spanning Sync is a full two-way sync. One person can continue to update their calendar on their Mac using iCal. But the other can log in to Google Calendar and create and edit events on that same calendar. Spanning Sync will make sure that the two calendars are kept in sync, with updates as often as once an hour.
