A modal dialog is an overlay window positioned within the within the same browser window. A modal dialog remains active and focused until the user has finished with it and closes it. While a modal dialog is active, the user is unable to interact with the rest of the page until the dialog is closed.

Set Modal Dialog as the Page Mode under Page Deifnition.

Dialog Header
This region position is anchored to the top and is useful for components such as a wizard progress bar.

Content Body
Place all of your content regions in this position.

Dialog Footer
This region position is anchored to the bottom of the dialog and is useful for placing buttons using the Buttons Container region template.