After you have loaded your scene,
- Click on the
this will bring up the Basic navigation keys
- Now you can click on the “ADVANCED” key to get this screen
which shows you that you can used their the PgUp/PgDn or Q & E keys to change the height of the camera.
Hope this helps…
Edit After rereading your post, I think what you may be asking is how to climb a stairs to get to the 2nd floor (I am assuming you have a stairs). Check out this Stairs Navigation Tutorial
Now, I hope this helps…