I've followed JWoods tutorial on object creation, and created my first object for myself. So, now I'm looking to try something else. I've searched, and I can't find a tutorial that I recognize as helping me create a 2-story version of Maxi's 1-story Elegant Column. This is something I would like to try, and I'm wondering if there's information not found in the basic object creation tutorials that I would need to know to make what I want.

You probably won't find a tutorial on this specifically. What you will likely need to do is make a temporary clone of the 1 story column to get its mesh and texture. Then clone an existing 2 story column. In your mesh editor, scale the 1 story column to be 2 stories. Then replace the mesh and texture of the 2 story column with your edited mesh. If it's the column that I think you are talking about, there is a second subset. Depending upon whether or not you combined the two into one mesh group, you can a second subset to the 2 story column via http://modthesims.info/showthread.php?t=103379. If you really want to get fancy, you could make the mesh edits but have the textures repo'd linked to the originals.