This video talks about using wikipedia for research at the college/university level. But the same rules mostly apply to High School. If you want to use wikipedia as a source for your assignments, talk to your teacher first and make sure it's acceptable!
This video gives you a great summary about what Wikipedia is and how it's different from other sources you might find in the library. What is a wiki? Who creates the info and how? What are its strengths and weaknesses as a research tool? These are all things you should know before you use it!