In order to play X-Wing Vs. TIE Fighter online, you need to consider the following steps.

1. Install the game - Copy the game files
2. Apply patches - Get necessary updates, files etc.
3. Networking - Port forwarding and firewalls
4. Set up Voobly - Enter the online gaming lobby to find opponents

After installing the game you need to apply at least the

• official X-Wing Vs TIE Fighter 1.14 patch
  which changes your z_xvt__.exe to Version 1.1.

If your game already works for online play, consider getting the

• Melee patch

You will need that to be able to play 1v1v1's 3v3's etc. This is called the melee patch or 10in1 melee.