you may edit your sources.list for modifying third line.
for this:
Code:
nano /etc/apt/sources.list
If you want to create a new sources.list , you may use netselect-apt.
Of course , you have to setup first. For this :
Code:
apt-get install netselect-apt
And type on your console:
Code:
rm /etc/apt/sources.list
--> Because sometimes program cannot create sources.list so we remove this file not to face any problem.
good luck..
I hope it helps...