What you'll need:
- An SSD
- SATA-to-USB cable
- Small screwdriver to open your laptop
- Torx head screwdriver for disassembling the hard drive
- SuperDuper (download it here)
Connect the SSD to your Mac with SATA-to-USB cable. Once it's connected, launch Disk Utility, and select your drive from the left sidebar. Then, head to the Erase tab, and click Erase. No need to change any settings, unless you'd like to give it a new name. This will format the drive and prep it for the next step.
Launch SuperDuper, and set it to clone your Mac's hard drive to the SSD. Then choose Backup All Files, and click Copy Now. When the process is complete, eject the SSD and shut down your computer.
Step 2: Remove the hard drive
Begin by removing your MacBook's back cover. There are 10 screws in total, including three longer ones. To remove the hard drive, use the regular screwdriver to unscrew the two black screws belonging to the bracket securing the hard drive. Remove the bracket and set it aside.
Gently lift the hard drive. You'll see that a ribbon is attached to one end. Carefully wiggle the connector -- not the ribbon itself -- to disconnect it. Remove the four torx screws attached to the hard drive and set aside.
Step 3: Install the SSD
Grab the SSD and screw in the four torx screws you removed from the hard drive. Then attach the ribbon to the SSD, and insert the drive in the same configuration as the previous drive. Re-attach the bracket. And finally, replace the back cover using the 10 screws. Now turn on your computer. It may take a couple of extra seconds as it gets acquainted with the new drive, but starting up your computer will be much faster than the in past.
http://www.cnet.com/how-to/upgrade-your-macbook-install-ssd-hard-drive/