Using Google Scholar?
Sync your Google account with USU. This will get you past paywalls for articles USU subscribes to by having you login with your A# and password.
Once you've identified some information sources, you need to decide whether or not you can use that information for the purpose you intend. You've probably seen a checklist of criteria to consider, and that can be helpful, but the real question to ask yourself is "how was this information created?" Different kinds of studies yield different kinds of information. The links below can help you make sense of it all.
There's a wide range of nutrition information on the web. Some of it is solid science and some of it is pretty sketchy. Here are some places to get ideas on writing science-based articles for the general public.