This is a tipical exam's exercise, you have to speak about a photo or picture that the teacher show you, so you have to be confidence describing you are seeing.
Some tips to start the description could be:
On the right / On the left (side)
At the top / At the bottom
In the background / in the foreground
In the corner
beside / next to
close to / near
in front of
On the left side we can see a man sit down on the top of a staircase.
On the right side there are three childreen playing together. In the background there is a big sun. While the children are enjoying together, the man seems not very happy.
Behind the girl, there is a boy chasing her. This boy is between the girl and the fair boy. Opposite to these boys there is a man, below this man there is a staircase ,and behind the man there is a advertisement with the message "The top".