Ah - a common problem.  Wireshark has installed and does not see any of the computer interfaces so you can do captures.

The answer to your problem is simple!

You need to give the Wireshark application root priviledges.

The best way to fix this (and any other application that needs root priviledges) is to change the way the program launches.

1. Right click on Applications
2. Now click on Edit Menus
3. Look in the Internet Tab and find Wireshark
   
   
   
   
4. Double click on Wireshark.  The launcer applet will appear.
5. In the field labeled Command: add gksudo in front of wireshark:
   
   

Now try launching Wireshark again and all the Interfaces will be there!!