The guile-vrr interface and Scheme console enable you to control the program by Scheme commands. Except for GUI and image viewing, you can access all the program functionality, such as image creating, loading, editing, saving, exporting or importing.
This book shows you only some basic examples of Scheme code but does not teach you Scheme systematically. To learn about the Scheme programming language, you might want to try some of the following:
C. Candolin: Scheme Tutorial – a basic tutorial for beginners. It is available online at http://www.cs.hut.fi/Studies/T-93.210/schemetutorial/schemetutorial.html.
H. Abelson, G. J. Sussman, J. Sussman: Structure and Interpretation of Computer Programs, MIT Press; available at http://mitpress.mit.edu/sicp/full-text/book/book.html).
Revised Report on the Algorithmic Language Scheme – a defining description of the programming language Scheme (http://www.schemers.org/Documents/Standards/R5RS/HTML/).