By using the process demonstrated in the lecture video, do master studies of the images provided. If you feel stuck on one of them, move onto another and come back to the first. This way you can look at it with a fresh eye.
For the first image, use the drawing method as shown in the Lesson.
For the second image, try the build up technique in the “speed painting” portion of the lesson.
For the third image, try to stylize the study as shown in the lesson.