This is a set of two tutorials originally developed by Miriam Posner, designed to give you your first hands-on experience with topic modeling, using the Topic Modeling Tool, a GUI implementation of MALLET.
Begin by following the instructions to install the Topic Modeling Tool on your own computer.
Once that's done, click through to begin Tutorial One: Messing Around with the Topic Modeling Tool.
You're also welcome (but not required) to explore Tutorial Two: Visualize Your Topic Model. This one assumes that you've been introduced to Tableau Public; you can begin by exploring Miriam Posner's Tableau Public tutorial if you like.
Have fun!