How do I shut down Apps in the new IOS 7?

Hi,

Just downloaded and installed the new IOS 7.

Can find no instruction as to shutting down the open apps. Used to be double click on the button, then touch and hold the app until the little shutdown spot appeared. Now it does nothing.

The 'apps' section in general, then tells you you should shut down open apps to save battery life...

Please tell me how to shut them down.

Thanks.