1. With Multitasking, you can use more than one app at a time on your iOS device. Double-click the Home button to see recently used apps.
   Note: Multitasking is available on devices running iOS4 and later with apps that have been developed to work with iOS versions 4 and later.
   
2. Swipe left or right to find the app you want to use.
   
3. Tap the app to open.
   
4. Swipe the app up to close.
   Note: Learn more from Apple support articles: Understand multitasking and background activity on your iPhone and Force an app to close in iOS