Note: if you have not done so, please read the introduction to Upgrading a PS3 Hard Drive before performing these steps.
Now that you have the hard drive carriage in your hands you will notice that there are four screws securing the hard drive to the carriage. Remove the four screws using a phillips screwdriver and replace the hard drive that is there with the new one you purchased, or have available, to upgrade the PS3 hard drive with. As previously stated, you must use a SATA laptop hard drive in this application.
The console firmware sets the read write access speed to the hard drive, so it is recommended to replace the PS3 hard drive with a similar SATA laptop hard drive that has more capacity than your current PS3 hard drive (I used a 160GB Maxtor). The PS3's original hard drive is a 20, or 60 GB SATA laptop hard drive rated at 5400 RPM, a similar speed replacement is recommended.
Be sure to re-secure the new hard drive in the exact location the old hard drive was on the carriage., and secure it with all four screws. You are now ready to move on to the next step.