How to download and install OS X El Capitan
1. Download the latest OS X from App Store or directly download from this link 2. Extract the pkg file. 3. Download DiskMaker X from http://diskmakerx.com/ 4. Install and launch DiskMaker X. 5. Select the location of the extracted installer (pkg) file. 6. Select Another kind of disk or An 8GB USB thumb drive. 7. Quit from DiskMaker X. 8. Eject the thumb drive or disk and insert it into the target Mac. 9. Reboot or start the Mac and hold the option button of the keyboard.