While the first step to understanding and growing your PLN is decidedly non-tech, it is nonetheless an essential step. Before you do anything else, take a large piece of blank paper, and draw a diagram of your current PLN. Start by putting yourself in the middle.
When I did this exercise, I used a white board, and it looked like this.
To create a slightly more formal - and more permanent - version, use any of the many mind-mapping apps. Here is a version of mine using the iPad app Fluent MM.
At the end of this section of the course, redo this exercise and compare the two versions of your PLN. Visualizing your network can help you get the most out of it.