At this point, the CD/DVD drive needs to be placed into the computer. The method for installing the drive will vary depending on the case. The two most common methods for installing a drive into a case is either through drive rails or directly into the drive cage.
Rails: Place the drive rails onto the side of the drive and fasten it with screws. Once the drive rails have been placed on both sides of the drive, slide the drive and rails into the appropriate slot in the case. Make sure to affix the drive rails so that the drive is flush with the case when it is fully inserted into the case.
Drive Cage: Slide the drive into the slot in the case so that the drive bezel is flush with the computer case. When this is done, fasten the drive to the computer case by placing screws into the appropriate slots or holes in the case.