If you do not have GNOME installed on your system, then there are many ways to install it
With a Linux distribution
Many Linux distributions offer GNOME as part of their package selections. Please check the documentation of your distro to see if GNOME is an available desktop enviroment.
Distribution specific help
- In Debian type "apt-get install gnome"
- In Ubuntu type "apt-get install gnome gdm"
- In Mandriva (formarly Mandrake Linux) select GNOME workstation from the installer.
- In Gentoo type "emerge gnome"
- In ArchLinux type "pacman -S gnome"
- In FreeBSD type "pkg_add -r gnome2"
- Installation on any distro will most likely require root access.
Garnome is a script that lets you compile GNOME.
If you want to try GNOME without installing, try a live CD that uses it such as Gnoppix, Gnome Morphix and Ubuntu Linux. If you want to easily compare GNOME and KDE, try a Fedora LiveCD - you can select which desktop to use at login time.
Other Operating systems
Sun Microsystems' Solaris offer GNOME BSD's can install it via ports or pkg-src. Just find the GNOME directory and type make install.