There are two ways to do that. First, you need to swipe left in menu or swipe until you found the tool folder.
Tadaa! You can see the flashlight tool right? Tap it and it would looks like this.
There is another way that is faster than this. Tap the drop down menu at the top of the screen.
See the flashlight tool option? It is at the top line. Tap it and you can use it. But, if you use the flashlight from the drop down menu, it will automatically off when your Oppo R1011 in sleep mode. It will turn on again when you turn on your phone.
Hope this helpful