Teleporters
are used to take you from one point of a map to the
other, if you find an area of your map has a dead
end in the place one of these in to keep the flow of
the level going.
For
this tutorial we need 2 rooms as shown below

In
one of the rooms we are going to place the
teleporter model and we do this exactly the same way
as we did in the misc_model tutorial but this time select
the model out of the teleporter directory.
Once
the model is in place load the common texture set
and find the texture called trigger.
okay we need to make a square brush about 128 units
high around the glowing tube bit of the teleporter
(the bit where you jump into.
If
the trigger brush is still selected then right click
somewhere on the grid and scroll down to Trigger>trigger_teleport
and click it, this makes that brush you just made
into a trigger_teleport entity.
In
the second room you have right click somewhere on
the grid and go to Misc>misc_teleporter_dest,
make sure that it's not stuck up in the air
somewhere or the effect won't work, keep it level to
the ground but not stuck in it.
This
is the fun part now so read carefully.
Select the trigger_teleport entity and then select
the misc_teleporter_dest entity by doing SHIFT+Click,
once both entities are selected hold down CTRL and
press K.
You
should see a nice red line going from one entity to
the other.

Compile
your map and go check it out.