There are a number of ways to locate a magazine issue.
From the home page click on a magazine category. You will then be presented with a list of publications in that category. Click a publication and you will then be able to view the issues. Depending on the publication, the issues may be presented by year or by volume.
You can also search for an issue or article by entering some search keywords in the search box at the top of any page. You can search for a publication name (eg. Two Wheels) or a specific issue (eg. Two Wheels April 1998). You can also search for articles on a specific topic (eg. Ford Fairlane).
For more search options you can use the search page. This allows you to search by keywords or by "tag". Contents of articles may have topics tagged in a specific format. For example, for vehicle models the tag format is make model series variant. You can also choose to search only a specific category.
The search page also allows you to limit the search only to issues you have. This requires you to have flagged which issues you have, of course.
It probably hasn't been added to the catalog yet? See Adding and editing publications, issues and articles for information on how to add to the catalog.