When approaching learning anything new figure out the high-level groupings of information. These can be viewed as the hierarchy, the chapters, the key areas, or the main topics.
The idea is to get enough understanding of what you are learning to create an organizing structure for placing the knowledge that you learn as you investigate the topic.
If you think of a book on a topic, the outline would be the chapters of the book. As you learn, you are filling out the details in each chapter.
In the end, you want to create a tree of knowledge. Start with determining the structure of the tree.