Please read How to view remote UNIX desktop from Microsoft Windows system to know more about accessing X server from a remote host.

X server comes with built-in support for remote desktop because of its client and server architecture. In Fedora Linux systems, X server is disabled on the network by default. That means the X client programs residing on the same host only can connect to X server. If enabled, typically X server runs on port 6000.

To enable X server on the network, search for DisallowTCP in /etc/X11/gdm/gdm.conf file and modify it to look like the following.

DisallowTCP=false

You may have to either restart the X server or reboot the system to get the settings in to effect.
If you still not able to connect to X server, check if it is really enabled on the network by looking at the list of actove ports in listen mode using netstat command.

If X server is enabled for network connections, you should see something similar to the following.

[neo@techpulp ~]$ netstat  -ntl | grep ":6000"
tcp        0      0 0.0.0.0:6000               0.0.0.0:*                   LISTEN
[neo@techpulp ~]$

If X server is not enabled for network connections, you should see something similar to the following.

[neo@techpulp ~]$ netstat  -ntl | grep ":6000"
[neo@techpulp ~]$

If you see some listen socket on port 6000 and still having problems in connecting to X server, most probably iptables firewall should be dropping the incoming connection. If so, disable firewall on port 6000.