First of all, you might want to build a map b4 you use this, like a basic room with two stories(you dont need to connect them. they could be two separate rooms with nothing in between but the grey void).
So... right click on your map(with nothing selected) an go to
trigger--->teleport and you should see a green trigger block. Hit "n" and eter these key/values.
targetname/teleport1
target/teledest1
so thats it for the trigger_teleport.
Now we need to put in a destination.
Right click with (nothing selected and select) Func---->teleportdest.
Hit "n" and then enter more key/values
targetname/teledest1.
If you enteterd this correctly there will be a grey line connecting the trigger_teleport and the teleportdest
then compile and enjoy!
Some Hints and Tips to Make Your Teleport addition Even Better
You could make a a secret door thats got the same color and thickness as the rest of the wall and put some locked doors near it to make em' think that buildings blocked off and then you could put your teleport inside.
Make your teleportdest in a secret room in the sky disguised as a cloud or a sky texture room so people could snipe(youd have to make a custom texture for the cloud thing of course)
By Master-of-fungus-foo-d
I'm actually thinking of putting some more stuff from this forum into tutorial format. Actually it would be even better if the authors themseves did it, my Wiki is open to everyone! Get in there and write atutorial, and make a page for yourelves in the "Contributors section" if you do. 