I just recently replaced my SuperDrive with my Mac's HD and put a new SSD into HD spot. How can I download and install the OS into the new SSD and copy all my files there? The SSD is smaller in size, so I want to only copy certain things.
If your Mac supports 10.7 or later, see the "Installing OS X on an external storage device" section in http://support.apple.com/kb/ht4718.
- Open Disk Utility when started up normally. Select the SSD, open the Partition tab, set the partition layout to one partition, set the format to Mac OS Extended (Journaled), and press the Apply button.
- Download an OS X installer from App Store and install it on the SSD.
You can copy the old files manually or by using Migration Assistant. If you can't download the installer from App Store, you can also download and install OS X from the recovery partition.