Do you know what Past participles are and how to use them?
1) Please, watch this video and this video to learn all about Past participles.
2) Learn to distinguish between Past Participles and Present Participle watching this lesson.
If you still don't understand the difference between the past participles and the present participles, read this post in Spanish.
Practice contractions with this video.(American English)
4) Use the above exercises to practice with your language exchange. You don't have a language exchange? What are you doing? You must have one if you don't have a teacher.
5) Let's learn some vocabulary about Halloween (it will be useful vocabulary for any occasion):
Halloween vocabulary exercises
This is halloween - a video with subtitles
6) Listen and read this story. You should learn all the vocabulary and practice pronunciation. And, for the most daring, read this article from The Economist.