Make sure your computer is open and locate the hard drive cradle
Next, remove the cables from the hard drive (the power cable and hard drive cable)
Pull out the hard drive out. If there is a screw holding the hard drive in, remove the screw first
To install a new hard drive, put hard drive in the cradle and plug power and hard drive cable in
Note: there are two different kinds of technologies for hard drives (IDE and Sata). Please make sure that when you buy a hard drive, your motherboard can support it (most newer motherboards use Sata technology). Also, please do not plug both power supplies in when installing a hard drive (both the Sata and IDE power) as it will cause your computer not to work