If you’d rather install Yosemite on the SSD then follow the How to Install Yosemite on a New SSD guide. Here’s link to a video on how to physically install the SSD as well as run the software installation.
Follow the prompts until El Capitan is installed.Choose to Install OS X on the formatted SSD. I’m still running OS X 10.10 Yosemite on the MacBook Air, and am resolved to wait until the first bugfix update build at least before committing to an OS X 10.11 El Capitan upgrade on my main machine, but I’ve been curious about El Capitan, which has been described as being analogical to what Snow Leopard was to the preceding OS X 10.5. Answer (1 of 2): Q: How do I upgrade my Mac from El Capitan to High Sierra A: According to Apple: > Check compatibility You can upgrade to macOS High Sierra from OS.Once complete, exit from Disk Utility and return the main menu.When the menu finally turns up, choose Disk Utility and format the SSD as Mac OS Extended (Journaled) with a unique name.Insert the El Capitan USB stick into the target laptop and power up.Physically install SSD into the target laptop.Change this to match the name of your USB stick. Where MyVolume is the name of your USB stick. However, you can't update your Mac to El Capitan 10.11 if your Mac runs on software later than Mac OS X 10.6 Snow Leopard. That's why most Mac users with old devices try to update their Mac to OS X El Capitan. Still, it also makes the existing OS obsolete. Sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia -volume /Volumes/MyVolume -applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app The latest software makes your Mac device compatible with the new technological developments. Create a bootable image from the El Capitan installer on a USB stick larger than 6GB.It will be downloaded to /Applications and be named Install OS X El Capitan.app If you are adding a drive to an existing setup, connect the SSD using a USB adapter or other external connection method and enter Disk Utility, or install the. If you're running a version of OS X older than 10.8, look into upgrading your OS X.
Select 'About This Mac.' The number underneath 'OS X' is your version number. Click the Apple icon at the top left of your screen. It might complain that you already have it installed but download it anyway. OS X Version: Mountain Lion (10.8), most models.