The default ASCX templates allow for different template layouts to accommodate 1, 2 and 3 columns, with pre-populated Containers and matching ID's to allow you to get started quickly with design integration. Refer to Template.css on how to change the Default CSS.
3 column layout (3column.ascx)
2 column layout (2column.ascx)
1 column layout (1column.ascx)
The examples above are a general indication of the layout and order of container. Default ASCX files are subject to upgrade changes.