A case contact is someone involved in the case in some capacity from outside your office. For instance, you might put the opposing counsel of the case or a guardian ad litem, etc.
To create a new case contact, click the 'Add Case Contact' in the Actions tab.
All information about contacts associated with a specific case can be seen in the case contacts list, as well as in the litigation overview. Both of these screens can be found by clicking links in the View Information tab.