Editing a file on Ubuntu
To edit any file on Ubuntu you can open a text editor like gedit from Applications->Accessories->gedit
or you can also open it from Terminal Window
Go to
1.Applications->System tools->Root Terminal
2.Type sudo gedit /etc/wvdial.conf
3.A Text Editor would open the file wvdial.conf
You may ask what is the difference between simply opening a file and opening it via Root Terminal.The difference is remarkable as it allows any file to be edited with root permissions
As Generally in Ubuntu, root account is locked.. you can’t simply edit .conf file or any file in etc,dev you need to have root access to edit it.