Asterisk GUI ... Using Pre-Defined Extensions

I have installed Asterisk GUI on a box which already had an Asterisk installation but after the installation of GUI neither am I able to use pre-defined extensions nor am able to view the pre-defined configuration. In the GUI if i select the file viewer and see sip.conf it shows me the version of the file before installation of GUI.

Can anyone guide me how can i install Asterisk GUI on a pre-configured Asterisk Box.