You can't just use anything you find on the web. You need to be able to prove the webiste is credible.
Use the code: Is it REAL?
R Reliability--Who is publishing this website?
E Evaluate the content--Does the content apply to your needs?
A Authority--Is the author an expert in this field?
L Links--Are they working? Do they lead you to other credible sources?
Use the powerpoint below to help you understand evaluating a website.