How to: Set Layout in a CheckBoxList Web Server Control
By default, the CheckBoxList control displays a single column of check boxes. However, you can specify any number of columns, and within the columns, you can specify how the items are ordered: vertically (the default) or horizontally. Vertical layout in three columns results in a layout such as the following:
A D G
B E H
C F
Horizontal layout for the same items results in the following layout:
A B C
D E F
G H
To specify column count and ordering
Set the CheckBoxList control's RepeatColumns property to the number of columns you want.
Set the RepeatDirection to Vertical or Horizontal. If you are setting the property in code, use the RepeatDirection enumeration, as shown in the following example:
CheckBoxList1.RepeatDirection = RepeatDirection.HorizontalCheckBoxList1.RepeatDirection = RepeatDirection.Horizontal;