Note: Select 3D Snapping on the Options Bar if you want a previously placed structural element to define one end of the column. This is the most accurate placement method. See Placing a Slanted Structural Column Using 3D Snapping.
In the drawing area, click where the column should begin in regard to the 1st Click elevation setting on the Options Bar.
Click where the column should end in regard to the 2nd Click elevation setting on the Options Bar.
The column is placed, defined by the 2 clicks and their associated levels.