The contact view lists the contacts in a narrow list in the middle of the window.

Use the +/- buttons below the list to add a new contact or remove the selected one.

You can clear a field of the selected contact with the "Clear field" button or by clicking on the label of the field. Cleared fields are not removed from the data source, but will no longer be shown in the contact view. You can add them back to the contact with the "Add field" button.

You can change the order in which the fields are displayed by dragging them up/down in the list.

Some of the icons to the right of some fields can be clicked. The homepage icon will open a preview of the homepage and the address icon will take you to Apples Maps application.