Where is sleep wake button on iPad mini2?

The sleep/power button is on the top of the iPad in the upper right portion of the device - if you are holding the iPad in Portait orientation with the round home button at the bottom.

If you want to turn the iPad off, hold down on the sleep button until the red slider bar appears on the screen. Then slide the bar to the right.

FYI

http://manuals.info.apple.com/en/ipad_user_guide.pdf