More than ever, Mac is the computer people love to use. And one of the biggest reasons is OS X. It’s what makes a Mac a Mac. With OS X, it’s simple to do amazing things and delightful to do all the everyday things. OS X El Capitan builds on the groundbreaking features and beautiful design introduced in OS X Yosemite, refining the experience and improving performance in lots of little ways that make a big difference. OS X El Capitan — it takes the Mac experience to new heights.
Homepage : http://www.apple.com/
If you have error during copy, eject and re-connect the pen drive. When Windows asks if you want to format it, cancel and run Image Writer again.
If the problem persists, disable your anti-virus software, it may be blocking raw write to the drive.
For OS X
Default boot loader is Clove
If you want to use Chameleon press 1 at boot