To be able to follow this tutorial you will need to know how to make a teleport.
Here is a simple teleport setup. One trigger_teleport and one info_teleport_destiantion.
Step 1.
Create an entity in the middle of the trigger_teleport and center it.
Step 2.
Select the entity and turn it into a info_landmark. Name it whatever you want. But i named mine TeleMark
Step 3.
Center the landmark in the middle of the trigger_teleport and inside of the floor like this
Step 4.
Set the "Local Destination Landmark" Property in the trigger_teleport to the name of your info landmark.
Step 5.
Cover up any holes in your level and it should be done.
Note: Try to place the teleports on the x or z axis and not the y axis. The screen jidders a little if you do so.
Here is a simple teleport setup. One trigger_teleport and one info_teleport_destiantion.

Step 1.
Create an entity in the middle of the trigger_teleport and center it.

Step 2.
Select the entity and turn it into a info_landmark. Name it whatever you want. But i named mine TeleMark

Step 3.
Center the landmark in the middle of the trigger_teleport and inside of the floor like this

Step 4.
Set the "Local Destination Landmark" Property in the trigger_teleport to the name of your info landmark.
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Step 5.
Cover up any holes in your level and it should be done.
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Note: Try to place the teleports on the x or z axis and not the y axis. The screen jidders a little if you do so.