Quake3World

I'm going to make a portal to another point in the level. But it will be like a pit. People will fall in it and warp to another area of the map.
I need to know what are the different types of portals. I need to know how to link them via trigger objects and everything. Thanks.

I tried using an example from a converted map. but it had too many layers. the top layer was a trigger but I couldn't tell where it was linked to.

Just put a brush in your pit, apply the texture: common/trigger on it.
Select the trigger brush and click RMB. Make it a trigger_teleport.
Place a target_position anywhere in the map you want to spawn from the teleporter-pit. Select your target_position and press N to check the direction you will spawn out from the teleporter.
Now select FIRST your trigger_teleport brush and next the target_position. Once you selected both just press ctrl&k to link your 2 brushes, a blue line should be drawn between if you did it right.
Here you go with your teleporter pit.

For reference: http://ws.q3df.org/level_design/teleporters/

If you also mean that you want to see yourself flying through the portal Team Arena style, that's done by teleporting to a separate map area and back.