Read through text explanations of thermodynamics online. Lecture notes and handouts are available online from universities. MIT Professor Z. S. Spakovszky has several thermodynamics resources available on his website at MIT, and a basic introduction to thermodynamics can be found on the Physics for Kids website (see Resources). Pay close attention to animations or pictures that accompany the text material. These will help you grasp the ideas and concepts the text discusses.
View videos about thermodynamics online. One series of lessons is available from MIT, and a set of nine video lectures about the second law of thermodynamics can be found at the Free Science and Video Lectures website. The University of Cambridge also offers a series of online thermodynamics videos designed to give students a basic understanding of the subject.
Review videos and text resources, beginning with material that is appropriate to your current level of knowledge about thermodynamics. Explore other topics as you feel more comfortable with more foundational concepts. Rewind and watch the videos again if there were parts that you did not understand.