Damn you make alot of topics..
First, click on the Point entities botton on the left. It sort of looks like a lightbulb. Then once you clicked on that, near the bottom right there will be a drop down arrow. Click it and find "Info_teleport_destination"
Place the entity anywhere you want your teleport to teleport to. Then click on the entity with the arrow, then press Alt+Enter. The properties window will come up. Click on "Name" Then enter in any random word into the text bar. REMEMBER WHAT YOU PUT THERE!
Now, find the aaatrigger texture.
Read if you need to help finding your aaatrigger texture:
It will be in the Half-Life.wad, or the zhlt.wad. http://www.superjer.com/files/zhlt.wad
<--- Download zhlt.wad here! Then after you downloaded it, click on Tools>Options... in Valve Hammer Editor. Now, click on the textures tab. Press "Add WAD" and find your zhlt.wad, and press "open". Click Apply, then OK.
Make a brush (meaning a block, piece... whatever u call it) with the AAATRIGGER texture. Click on the brush with the arrow thing. Then right click on it in one of the 2D views. Click "Tie to entity" A properties window will appear. Make the "Target" to what you named your Info_teleport_destination earlier.
Now it should work.