When faculty ask students to use "peer-reviewed journals", they most often mean academic journals instead of, for example, popular magazines or news magazines. 

To find academic and peer-reviewed journals,

1. use the main library search box in the middle of the page at Library.colum.edu. 
2. Enter your search terms. 
3. When viewing your search results page there will be a list of options on the left to "Refine Results".   
4. Scroll down to the option to "Filter by Format" and check the box for "Academic Journals".
5. Allow the page to reset, and the results listed should all or nearly all be articles from academic journals.