You know it's important to evaluate information you find on the open web. It's also a good idea to evaluate other sources--even those from scholarly books and journals--to understand how the information and ideas they express are relevant to your research.
Although you may decide to use any or all of the information you find, you need to evaluate that information so that you understand where the information comes from and how the ideas are relevant to your research.
For example, if you choose to include biased information or out-of-date scientific theories, you must recognize those materials for what they are and indicate in your paper or presentation why that information is important within the context of your research.
Questions to ask as you evaluate the sources you find and the information and ideas they present:
Who is the author?
Why was the source written?
How was it written?
Why was it posted or published?
How stable is this information source?