The sources you use in college must be authoritative. That is, they must be written/produced by people who have expert knowledge about the topic under consideration.
Not all websites are produced by experts. Because anyone can build a website, there are thousands of sites on the Internet that are inappropriate for college-level research. How do you decide what's authoritative for your topic and what isn't?
This guide gives you some things to think about as you begin to evaluate websites.
Read these books online through the library, or just skim a few chapters: