Before you begin looking for scholarly articles, which are specific research studies, you need to find some basic information on your topic using reference sources, such as reference databases, reference websites, or print or electronic encyclopedias. These sources are great for getting the overview of a broad topic. Sometimes reference sources can also point to scholarly articles.
For example, use a reference source if you want to learn about gluten-free diets in general.
Once you get some background information, you will have more context. This initial research can help inform your search for scholarly journal articles, which report the findings of a research study, such as an experiment, survey, clinical trial, etc.
For example, after you learn that gluten free diets can help people with celiac disease, perhaps you want to find articles that measure the effectiveness of this kind of diet is in lowering particular effects in celiac disease.