How do you burn an iso bootable?

[Atari]

Well long story short, my copy of windows XP broke, so i had to download one....... Anyways, using nero express, how can i burn this iso of windows xp bootable? I know, dling windows is bad... But i need to reformat. Can i just burn it with nero as "data"?

 

[Atari]

..................... i burned it into a cd as image, but it won't load when i put it in cd drive and restart comp.. help