THIS WILL TEACH YOU HOW TO MAKE DOORS!!!!!!!!!!!!
first create your door
easy
now
use the "ORIGEN" texture
click browse and just type ori, you'll find it
it looks like a small green face
this is a special texture, equivalent to AAA_TRIGGER
but instead of saying trigger something
it says axis
your doo should look something like this
the origen texture is like a door hinge
[EDIT] to make the door spin up and down. in the flags tag of the options, there should be a flag "y-axis". check that off and it sould work. note if it doesn't check off "x-axis. i don't have hammer in front of me to check exactly what the flags are. there its should be like what i just said[/EDIT]
now
once you have created the door at it looks somewhat like the image
right click on it and make it "func_door_rotating"
and theny modify the properties as you wish