You all have probably done a sketch of ideas on the back of a napkin, on a big piece of paper with lots of coloured pens and perhaps post-it notes. Being able to write ideas down in brief form, put circles around them and then draw lines between the circles and so on is a practice with which you will be familiar.
To call this process mind mapping may be crudely accurate. To me it is kicking ideas around, looking for connections, using a diagram to help you think differently about the associations and the ideas.
The label mind mapping is used extensively to describe/promote software that supports you doing this process on a screen. I'm not at all convinced that doing this using software is as much fun or as effective as doing it with paper and pen.
It's a useful way to begin to think about your topic or focus. You can just scribble down some of your initial ideas and then add to them over time, and then add notes to papers you find and so on.
This is an excellent way to begin your task for this course. A big piece of paper and start scribbling on it. You can make notes on it and in your notebooks.