I have world editor. I want to know how to add an enemy to face. I can..

To get a enemy to face you must do the followin things:

First press the button named scenario at the top of the screen.
There you wil find a option named player properties, click at it.
Now you should get a box where you can seee a overwiew of all the twelve players that you can include in your map. You can see that the player on the top (player red) is named user under the controller option in the box.
Now you click on the controller option for blue (or wathever player you want to add) in the box and choose computer. You can also change the race option in the box if you want another race to fight aiganst. When you has done this you click OK chose the second player at the tool palette and set out a start location for him.

Now you got a enemy. If you want a player you do it exately the same way but instead of choosing computer at the controller option you choos player instead.

I hope this can help you. But remember that it take some time to learn all at the map editor. Theese are just some og the basics.