The stratosphere is an area of our athmosphere ranging from about 10 to 50 kilometers in altitude. It's a very strange place. If you where to fly at about 30 kilometers high above, the ground, your conditions would be more similar to what you would find in Mars than to our usual ones. Air pressure is about 1% of the one we are used to, and temperature is around 30-50 degrees below zero.
Most of the athmosphere is below you, and for this reason the sky is black even during the day. Also, from that altitude the curvature of the horizon begins being noticeable, and the Earth starts appearing as a large ball.
Surprisingly, recent evolutions in technology have made it relatively easy to send a camera there, take photos and come back safe to earth.
All you need is a weather balloon (scores of them are launched every day to collect information for weather forecasts), a small parachute, a GPS sending data to a computer that transmits its co-ordinates to earth, and of course a camera. While the ballon rises in height, the air is always less dense, and the balloon expands.
When you arrive to a certain altitude (usually just above 30km) the balloon has exanded so much that it suddenly bursts and your capsule falls back to ground, slowed by the parachute. By rushing to the co-ordinates that are sent back via radio, you (hopefully) recover the capsule, the camera and the photos.