Thank you.
I have read the debian wiki on sources.list and about nano editing the file.
I installed debian using debian 8 dvd 1 64bit iso. It turns out, that the
sources.list gets config for cd updating only.
It looks like this
>>
#
# deb cdrom:[Debian GNU/Linux 8.0.0 _Jessie_ - Official amd64 DVD Binary-1
20150425-12:54]/ jessie contrib main
deb cdrom:[Debian GNU/Linux 8.0.0 _Jessie_ - Official amd64 DVD Binary-1
20150425-12:54]/ jessie contrib main
# Line commented out by installer because it failed to verify:
#deb http://security.debian.org/ jessie/updates main contrib
# Line commented out by installer because it failed to verify:
#deb-src http://security.debian.org/ jessie/updates main contrib
# jessie-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/ jessie-updates main contrib
# deb-src http://ftp.debian.org/debian/ jessie-updates main contrib
>
# deb cdrom:[Debian GNU/Linux 8.0.0 _Jessie_ - Official amd64 NETINST
Binary-1 20150425-12:50]/ jessie main
# deb cdrom:[Debian GNU/Linux 8.0.0 _Jessie_ - Official amd64 NETINST
Binary-1 20150425-12:50]/ jessie main
deb http://ftp.us.debian.org/debian/ jessie main non-free contrib
deb-src http://ftp.us.debian.org/debian/ jessie main non-free contrib
deb http://security.debian.org/ jessie/updates main contrib non-free
deb-src http://security.debian.org/ jessie/updates main contrib non-free
# jessie-updates, previously known as 'volatile'
deb http://ftp.us.debian.org/debian/ jessie-updates main contrib non-free
deb-src http://ftp.us.debian.org/debian/ jessie-updates main contrib non-free
# jessie-backports, previously on backports.debian.org
deb http://ftp.us.debian.org/debian/ jessie-backports main contrib non-free
deb-src http://ftp.us.debian.org/debian/ jessie-backports main contrib
non-free