To access the Cocoon Camera, tap on the plus button in the center of the tab bar at the bottom of the screen. When the Composer appears, tap on the Camera tab at the bottom of the screen.
The Cocoon Camera is very simple: to take a picture, press the circular white button. You can take as many pictures as you like before decided to post – each time you take a photo, you will see a small thumbnail appear below the viewfinder. When you are ready to post the pictures you've taken, press the blue arrow in the bottom right of your screen.