How to change the software sources to Internet?
 

I installed Debian using a CD. Everytime when I try to install some packages in Debian, they're asking for the CD-ROM. I heard that I need to change the source in /etc/apt/sources.list. But I don't know how.

At present, the content of my sources.list is

---------------------------------------------------------------------------------
#

# deb cdrom:[Debian GNU/Linux 6.0.3 _Squeeze_ - Official amd64 CD Binary-1 20111008-14:36]/ squeeze main

deb cdrom:[Debian GNU/Linux 6.0.3 _Squeeze_ - Official amd64 CD Binary-1 20111008-14:36]/ squeeze main

deb http://security.debian.org/ squeeze/updates main
deb-src http://security.debian.org/ squeeze/updates main

# squeeze-updates, previously known as 'volatile'
# A network mirror was not selected during install. The following entries
# are provided as examples, but you should amend them as appropriate
# for your mirror of choice.
#
# deb http://ftp.debian.org/debian/ squeeze-updates main
# deb-src http://ftp.debian.org/debian/ squeeze-updates main
-----------------------------------------------------------------------------------------------


I'm new Debian. I've experienced only ubuntu. Please help me. I wish to know if I can install Synaptic Package Manager in Debian too...

The first deb cdrom entry is commented out with the # sign. Do the same to the second one, and apt won't prompt you for the cd any longer.

You probably also want to add this couple of lines to your sources.list:

(This will enable the main software repository, as well as the source code repo).

Just to answer your last question, on a standard Debian install Synaptic should be installed by default. If not you can easily install it, Synaptic is a Debian application.

# Official Debian mirrors http://www.debian.org/mirror/list
# Also at http://ftp.debian.org/debian/README.mirrors.txt
# SourcesList - Debian Wiki - http://wiki.debian.org/SourcesList


While Synaptic is nice(and is easily installed), you would be better off in the end to learn how to use apt-get/aptitude.

# aptitude user's manual - http://algebraicthunk.net/~dburrows/...titude/doc/en/
# Apt - Debian Wiki - http://wiki.debian.org/Apt
# Aptitude - Debian Wiki - http://wiki.debian.org/Aptitude

Until you are comfortable using apt-get, Synaptic would be useful. Ubuntu's version is the same as Debian's original, so it would be easy for you to use. Just go to sources and click on the square to remove the check mark from the CD entry.