Read this first:

The Reading Aids for the Collected Works of Shinran are currently under construction, and will be made available within the next few months. These tools will include a Glossary of Shin Buddhist Terms (currently available!); Introductions to the various works contained in Vol. I of the Collected Works; A List of Passages for Teaching, Practice, and Realization; Notes on Shinran's Readings; and an Index of Names and Titles Cited.

Navigation of the frames is simple...select your tool (currently only the glossary) in the dropdown menu...and use the right frame for further navigation. You can also use the dropdown menu to switch between The Collected Works of Shinran and The Reading Tools.