how to install gui for debian

I have installed debian in my old computer(extremely slow) with minimal installation. It is showing me terminal. I tried installing GUI as follows:

 $apt-get update  //done successfully
 $apt-get install x-window-system-core gdm

It is showing is me error saying that: Unable to locate x-window-system-core and unable to locate gdm. Please anyone help me as soon as possible

The package in debian for the x window system is called "xserver-xorg-core", not "x-window-system-core" which would be your problem.

So you would install it with: apt-get install xserver-xorg-core gdm.

If you want your system to be light-weight I wouldn't go for GDM as a display manager as it really isn't very light. I'd suggest either LightDM or SLiM instead.

Lastly, you'll probably also want a Window Manager as the xserver on its own only gives you the windows, nothing more. An example of a light-weight window manager is Openbox.

See the debian wiki for details and examples:

http://wiki.debian.org/DisplayManager

http://wiki.debian.org/WindowManager

http://wiki.debian.org/Xorg

To install GUI (Graphical User Interface) for debian

Gnome

# apt-get install aptitude tasksel
# tasksel install gnome-desktop --new-install

KDE

# apt-get install kde-standard

XFCE

# apt-get install xfce4 xfce4-goodies thunar-archive-plugin

There are more options to choose from this page http://namhuy.net/1085/install-gui-on-debian-7-wheezy.html

Just replace your previous second command or line with this one:

Previous commands:

$apt-get update
$apt-get install x-window-system-core gdm

New working commands:

$apt-get update
$apt-get install x-window-system-core gdm3