Step #1 Click on the Admin Tab
Click on "Configure Custom Dispositions" in the lower right of the screen.
Enter your Custom Dispositions under "Add Custom Disposition" and select the "Add" button on the right.
Once you have added your Custom Disposition log out and then back in to see your changes from the Contact View tab.
Step #2 Enable Show Custom Disposition for each user
Click on the Admin button (head icon bottom left of screen)
Click on the yellow pencil below users name
Select Tabs and Appearance
Check the Show Custom Disposition