The second entry in the official Skyrim Creation Kit tutorials covers the basics of layout. For more information, visit CreationKit.com.
0:22 - Creating a New Cell
1:48 - Prep for Building
2:45 - Align to the Origin
3:32 - Snap to Grid & Snap to Angle
4:09 - Building a Basic Room
7:27 - Search & Replace
8:07 - Building a Hallway
9:17 - Layout Time-lapse
ESRB RATING: MATURE with Blood and Gore, Intense Violence, Sexual Themes, and Use of Alcohol.