How To : Apple : Macboook Pro 2011 : Replace Hard Drive with SSD and Clone and Install

Apple Macbook Pro 2011 Hard Drive Replacement

Purchase a 2.5" SSD Hard Drive (with a 2.5 hard drive enclosure if possible).

If the 2.5" SSD does not contain a external hard drive enclosure, you can purchase one separate from Amazon.Com, just do a search for "SSD Hard Drive Enclosure"

Attach the 2.5" SSD Hard Drive enclosure to the computer. Most do it through a cable.
If the new 2.5" SSD Hard Drive storage space is larger than your existing hard drive, skip to Step 3. If the If the 2.5" SSD Hard Drive you bought has a smaller storage space than your current Hard Drive, you will need to resize the current drive first before you can begin cloning. You will need to Partition the Mac hard drive so that it is now the same size or smaller of the SSD Hard Drive

First Open Disk Utilities
Then click the hard drive
Change the space of existing hard drive so it's smaller than the new 2.5" SSD Hard Drive

Turn the Macbook over and use a small Phillips screw driver to remove the bottom plate.

IMPORTANT: Set the startup drive to Macintosh Hard Drive. If you fail to do this, your Mac will be slow.