You should enter the VFS via an instance of the VFS class, e.g. the following code creates a new virtual filesystem and then resolves the URI for a local ZIP file to a virtual folder.
VFS vfs = new VFS();
URI uri = new URI( "file:/afolder/archive.zip/" );
Vfolder folder = vfs.resolveAsFolder( uri );
Now you've got the virtual folder you can examine it for other folders and files. e.g. if the archive has a file called "file.txt" we could access it using:
VFile = folder.checkVFile( "file.txt" );
There are two different methods for accessing the folders and files a
given folder contains. They either start with check or
get. The check methods will check to see if the requested
file or folder exists, throwing an exception if no such file or folder
exists. The get methods do not perform any of these checks and will
always succeed.