I am unable to view the GUI mode of the Fedora Linux machine through the Xmanager. I don't have issues in viewing my Solaris boxes. Please let me know if anything needs to be done about this?

You need to tweak

/etc/X11/xdm/Xaccess

and

/etc/X11/xdm/xdm-config

See XDMCP-HOWTO

I am unable to find the below mentioned directories and its files. Do I need to install something or can I create the directories and files manually?

cd /etc/X11/xdm
-bash: cd: /etc/X11/xdm: No such file or directory

[root@localhost init.d]# cd /etc/X11/kdm
-bash: cd: /etc/X11/kdm: No such file or directory

[root@localhost init.d]# cd /etc/X11/gdm
-bash: cd: /etc/X11/gdm: No such file or directory

no XF86Config file in /etc/X11

hi,

the xdm, kdm, gdm -- those are executables, you cant find it using cd,
use which xdm, and so on.

the problem is that you havent install X package tree.

HTH,

Cheers.