First, read the English article below.

This looks like a gray gear icon located on your Home screen.  The switch should turn green. This option will be under the AUTOMATIC DOWNLOADS heading. It will enable your iPhone to automatically download updates for existing apps on your device. The switch should turn green. It will let your iPhone use your carrier’s mobile data plan to automatically download app updates. Your iPhone will still use Wi-Fi to download updates if you’re connected to a Wi-Fi network. Cellular data will only be used when you don't have an available Wi-Fi internet connection. 

Now, please write a short abstract for it in Chinese. Abstract:
打开iPhone“设置”程序。 滚动菜单，点击iTunes与App Store。 将更新开关滑动到打开位置。 将使用蜂窝移动数据开关打开，开关变成绿色。