1. Most databases offer users a way to limit their searches to "scholarly" and/or "peer reviewed" articles. This is the easiest option to use if available.
2. You can find the journal's website or look at the print copy of the journal. The site and print edition will usually include information as to the nature of the publication including if it is peer reviewed or refereed.
3. If it is difficult to find this information on the site, try to find the "Instructions for Authors" pages or links. Articles are considered to be refereed (peer-reviewed) if authors are asked to submit multiple copies of the same article. The editor usually wants extra copies to send to reviewers.
4. Check the journal to see if there is an editorial board. The members of this board usually serve as reviewers.