To find articles in journals, you need to search databases other than the library catalog. (The library catalog lists the journals the library owns, but not the articles contained in them.) Databases used for looking up journal articles are often called "Indexes" or "Abstracts".
Sometimes the index where you look up an article will have the text of the article online (you can click and read). Other times, the index will have a citation to the article -- this lists the name of the journal, and date the article appeared. You can search for the name of the journal in the Library Catalog. If the library doesn't have the journal, you may be able to get the article through Interlibrary Loan. In some cases, the journal is available to read online, in which case the catalog will have a link to it.
Below are some databases that can be used to locate newspaper and journal articles: