Before starting the exercise, I was a little confused by the course matter. It seems that I need more practical explanations when technical matters are concerned, so I have searched in the internet and have found the following link very interesting
The video was very useful and I got an idea of how to create a cheap diffuser. The whole idea is use a diffuser in order to turn a hard light into a soft light.
I have used a transparent packing plastic material with some tape and have lightly covered the spotlight. The photo below shows how the lights have been softened to create a more uniform background. The angle I have used is not the correct one but i think I have managed to understand the difference.
The covered spotlight:
It is clear that the light is soften even in the way by used the cheapest material available.
Finally, I have also tracked down this link which I find very interesting and inspiring