Help add remove programs problem in ubuntu

recently while installing screenlets in ubuntu as given in ubuntu customization guide i have changed the repositories links and added repository list of screenlet server in ubuntu add remove program servers in third party software tab .now i am unable to open synaptic package and add remove program it says to change the things in sources.list .i have found sources the list in etc/apt/source.list but not able to save it .am i doing the right thing? how to solve it?how to login as root as i don't have root user privilege what is root login is and user name?

thanks in advance

#487478

Run this (using Alt+F2 as far as I can recall):

gksu gedit /etc/apt/sources.list

And it should ask your administrator password and then let you edit the file.

#487497

using gksudo is better than gksu.

#487500