A disc image can be loaded into burnatonce either by double clicking it in explorer or by choosing 'Load New Image' from the 'File' menu.  Also a data or audio cd project can be loaded by pressing 'Compile' in the relevant mastering window.

Once an image or project is loaded into burnatonce it is displayed in the lower left hand corner of the main window.  After checking the write settings the disc can be written by simply pressing 'Write'.