While the Library Catalog can tell you if the library owns the journal Early Music and which issues can be found in the library, it cannot tell you what articles may be found inside; that is the job of a periodical index, a database of the articles contained in journals, usually on a particular topic, e.g. music.
Once you find an article you would like to access, full text may be available by clicking on the button that looks like this:
This button will let you check to see if the library has access to the article online or in print. If not, you can borrow the item using Interlibrary Loan.
For more information, try this guide to getting fulltext articles.