Use Library Databases
Many of the databases provided to you through the Libraries allow you to narrow your search to return only peer-reviewed results and leave out any content from the journal that is not peer-reviewed.
This process differs from database to database, but is often as easy as checking a box that says Peer-Reviewed, Scholarly Journals, or Refereed.
Use Google Scholar
You can also use Google Scholar to find peer-reviewed journal articles, but be careful: not all content found through Google Scholar is peer-reviewed.
Google Scholar doesn't have an easy way to limit to only peer-reviewed results. You might need to do a little research to determine if the content you find is actually from a peer-reviewed journal.