Drag and drop files or folders into the main program window, adjust your volume name as desired and click the "Burn" button. Disk Burner, that is built into Mac OS X, burns an entire disk at once whether you have used all the space on it or not. CD Session Burner lets you burn as many smaller volumes to the disk as you like until the space is all used up. That makes it perfect for doing incremental backups as you work on projects. When you use a multi session disk each session will mount as a separate volume.