Exactly how do you make Xbox game backups?

[Holomatrix]

sorry to bud in, this is my first post. Are most games on DVD disks which are to big for a CDR and if you found one that was small enough could you not download it with your DVD rom on the computer then burn to CDR? why do you need to hook it up to the PC? also can some one point me to a tutorial step by step on XBOX backups?

Thanks