How do I add a link from a Calendar entry to a Contact entry?
You may need a newer version of Android/device or at least a more capable calendar app that can run on Gingerbread. The modern stock version of the Calendar (I think from 4.0 onward) lets you assign people from your contacts to appointments. Only about 4% of Android users are currently running Gingerbread so you're kind of in a small minority and may not find much help because so few of us are running anything earlier than Android 4.0.