There are many guides that will help you open your ports, if you have never done this before. You have to make sure of a few things 1st;

- Are you connected through a router?

If your connected through a router, you will need to look up how to open ports for that router brand.
Best way to do it would be to Google the name of your router with port forwarding. (Example: Dlink how to port forward )

So Because there are many guides to port forwarding through the windows firewall, the best ones are from the microsoft website.

Click here for Port Forwarding Guide for Windows Firewall [windows.microsoft.com]

NOTE: If your on a router, you have to open the ports on the router AND the windows firewall.

So we are running through the default Unreal Engine ports. Heres the ports that need to be opened.

Unreal Ports:
UDP: 7777

Steam Ports
UDP: 27000 to 27015
TCP: 27015

So now, you should be able to host using the multiplayer button in the game, however you can also run a dedicated server program, and here's how.

Locate the game folder in your steam folder. Goto "C:\Program Files (x86)\Steam\steamapps\common\Ukrainian Ninja\Binaries\Win32"

Right Click and make a shortcut to Udk.exe. I usually place the shortcut on my desktop

Right click the shortcut and goto properties.

You will see under the Target info, the location of the udk.exe. Scroll to the end of the target info and add the following to the end of it.

Server UN-Townstead?Game=UNGame.UN_GameInfo

so it should look like this in total; "C:\Program Files (x86)\Steam\steamapps\common\Ukrainian Ninja\Binaries\Win32\UDK.exe" Server UN-Townstead?Game=UNGame.UN_GameInfo

And your ready to start the server. Just load the shortcut, and the server program will start.

Your server will now show up in the server browser list.

The server file is located in the UDKGame.ini File, (Ukrainian Ninja > UDK Game > Config ) you can change the server name there as well as what map to load 1st.

The map names are the following;

UN-Townstead
UN-TrainRide
UN-TheCity
UN-TheSewers
UN-HiddenForest
UN-Convoy
UN-ChemicalFactory
UN-ReturnToCity