Click on the eBook/ejournal link on the main library page.
Search for the journal title, subject, or if you know the journal issn/isbn number.
Search for the relevant vender and date range:
For the example below, if you wanted the most recent issue of Nature Immunology for January, you would click on the Nature Journals Online link that has issues up to the present.
The journal TOC can then be browsed to find articles of interest by journal volume and issue
You can then read the article on the device or download the article.