Q: how do i shut apps off that are idling?

Double click the home button. Hold on any open app until red - appears.

http://img197.imageshack.us/img197/9099/newn.png

Double tap the round home button, then press on one of the apps on the bottom line until they jiggle, then tap the X on the top left of each app, that will close them for you.

Define idle: adjective

1. not working or active; unemployed; doing nothing: idle workers.

2. not spent or filled with activity: idle hours.

3. not in use or operation; not kept busy: idle machinery.

As are most iOS apps > iOS: Understanding multitasking