Googling the website has a windows download and then separately an os x download.
It's possible to do a clean install of OS X El Capitan on your Mac - or on a new hard drive, if you're upgrading or repairing your Mac - but it takes a bit of work. If the installer asks to unlock your disk, enter the password you use to log in to your Mac. Click Continue, then follow the onscreen instructions to choose your disk and begin installation. After starting up from macOS Recovery, follow these steps to install macOS: Choose Reinstall macOS (or Reinstall OS X) from the Utilities window.
