It depends on your computer and OS...but if you have a CD burner you should have some sort of writing software. In many cases, all you have to do is open the burner drive window, then open the window of the directory where the file is and adjust them so you can see both on the desktop. Hover the mouse over the Excel file to highlight it, right click and drag the file to the CD burner window. If you want to burn several files use the burner software since it will allow you to compile all the files you want to transfer and check they'll fit on the CD before you burn and finalise it.