Scholarly Articles are written by scholars for other scholars. Look for them to:
Magazine (Popular) Articles are written by reporters for the general public. Look for them to:
Often scholarly sources are peer-reviewed. Here's how a scholarly source becomes peer-reviewed:
Peer-reviewed articles are the highest quality of scholarship articles. They will be your best resources for your paper, which is why your instructor is wanting you to make sure you get them. You paper will be no better than the research you use to write it, so always select the best material you can.
You will NOT be able to limit your results to scholarly (peer reviewed) articles on the internet (or using Google).