Use the Now Up-to-Date Preferences pane to set how you want the communication between Now Contact and Now Up-to-Date to occur. Especially important is establishing the files you want to connect.
Options
Calendar file button: Click to select your Now Up-to-Date Calendar File.
Always link Events to calendar checkbox: When checked, every new Calendar Event you create automatically links to the selected Calendar File.
Transfer to Now Up-to-Date when creating new events checkbox: When checked, Now Contact automatically transfers you to Now Up-to-Date when you create a new Calendar Event. Or leave this box empty, and switch to Now Up-to-Date to modify Events that you've created in Now Contact.