What you should know how to do:

Understand the basics of the editor.

This tutorial will teach you the fundamentals of Zones and how they apply when building with Unrealed.

Clicking on the Zone/Portal button in any of the viewports of the editor will display by color all the different zones in your map. This is very useful to determine if your map is properly zoned and especially for troubleshooting zone problems. Clicking on the Build Options button will bring up the following dialog box:

The Stats tab will inform you on how many zones the map currently has. The Unreal engine is limited to 64 zones. Any more than that will end up with all the zones merging into one - NOT a pretty sight! Each zone in your map has the benefit of being a unique area because you can change the properties of that zone. You can fully customize almost every aspect of the environment by the use of the ZoneInfo which you add through the Actor Class Browser button .

The ZoneInfo is located under Info>ZoneInfo. Highlight it with your mouse then in the 3d viewport right click to add the ZoneInfo. I have created a small basic level to demonstrate how to seal off and zone your map.

As you can see from this top down view there are two large rooms connected by a smaller room and are labeled A, B, and C. Currently only C has a ZoneInfo. Clicking the Zone/Portal button would show you that they are all the same color indicating they are in fact only one zone all adhering to the properties of the ZoneInfo in room C. I am going to create a sheet brush that has the exact dimensions of room B and add a zone portal on each side of the room to seal it off. The dimensions of room B are 512*512*512.The sheet brush is in fact a only a sheet so we will only need to worry about the Height and the Width..

Selecting AX_XAxis will rotate the brush so that you do not have to do it manually. Using every viewport, line up the brush so that it is water tight around the edges.

I personally like to pick a unique texture to use at this stage. Click the Add Special button and select the Zone Portal from the  Prefabs drop down menu. I always select 2 Sided as well.

Once you click OK the zone portal will be put into place. Do that on the other side of room B and you will now have 3 distinct zones in all the rooms.

Remember to rebuild after adding the zone barriers. Then add ZoneInfo's to the other two rooms. Now you are ready to start editing the properties of your zones! One of the things you should do is name each zone with unique names. Right click on a ZoneInfo to bring up the ZoneInfo Properties dialog box. LocationStrings is where you would enter a name for your zone:

Only place portals in small areas so that CPU utilization is kept to a minimum. Large portal areas can slow down the game.

That is all you need to know to start working with zones. A map that is zoned well can make all the difference.