We have many databases that will provide links to psychology research study articles. Your teacher probably would like that you use PsycInfo (which includes PsycArticles) for your research as this is the authoritative professional index to psychological literature.
However, not everything in PsycInfo--even content from "peer-reviewed" journals--will be a "research study." So it is important for you to understand what to look for as you evaluate the articles you find when doing your research.
We have a guide, with screenshots, that reviews the components of a psychology research study, you can view this guide here.
Another thing to remember when you are using PsycInfo is that the majority of articles in PsycInfo are not full-text there. But if you click the "Link to Full Text" icon (look for the green dot) on an article record, you can check for full-text in another database. Many of the articles indexed in that database will be available through linking.