Many online sources are plagiarized or of questionable quality. When using online sources, ask yourself the following questions: Who is the author? What are his/her credentials? What possible biases exist? When was this source published?
When creating your project, remember to cite everything you did not write/create/think up on your own, including images/graphs/charts/maps you borrow from online sources. For more info, take a look at the following:
Below are some useful websites to help you format your sources correctly.