Choose Archie… from the File menu and fill out the fields one by one.  The Server is the archie server to query.  The search field is where you specify what you want to find, it can be a substring, pattern or regular expression.  Patterns are like unix or messy-dos file patterns, and they will be converted to regular expressions.  Specify the maximum number of files you want retrieved (you may get less than this number though).  Then click Search, and wait a while.  When a search is completed, the matches will be shown to you.

If you know where the file is, you can also choose Get… from the File menu to fetch it directly, or to fetch a directory listing and then look around from there.  Or use the List Bookmarks command to give you a bunch of sites to start wandering around.

You can select entries and copy it (formated as host:path), or option-copy it (formatted as ftp://host/path), or double click it, and Anarchie will fetch it for you.