how do i close an app so its not still running in the backround
After closing the app, double tap on the home button and then locate the app. Afterwards, swipe UP to remove it from the list. Also, go to Settings-General-Background App Refresh and disable it, if it is listed. NOTE: I'm assuming your device is running iOS 7....
The 3rd gen iPod Touch is not able to run iOS 7... the way to close apps (on iOS 4 or higher), double tap the home screen, press on any icon in the task switcher list until the icons begin to wiggle... then tap on the (-) for the apps that you want to close.