As I promised, here are my book recommendations (as well as websites) that will help in gaining different aspects of making and understanding music.
For your music theory studies:
Tonal Harmony: with an introduction to twentieth-century music By Stefan Kostka and Dorothy Payne
This is a standard textbook used in many universities and is used at my universities freshmen theory classes. Its straight forward and newer editions come with workbooks and CDs that accompany the text.
www.musictheory.net
This site has the basic beginnings of what you need to know in music theory and aural skills. The site comes with exercises and tools for later studies. It also has accompanying apps for both theory and aural skills.
Counterpoint by Kent Kennan
A much more advance book on just counterpoint, how to study it and how to write it. Its very thorough but can go over ones head very easily.
Analysis of Tonal Music: A Schenkerian Approach by Allen Cadwallader and David Gagné
An even more advance theory text that uses schenkerian theory to analyze tonal music. Might want to put off this book until you fully absorbed the others.
Structural Functions of Harmony by Arnold Schoenberg
As the title suggest, its a book on harmony. However, it is not a how-to on harmony, but the theories and functions of tonal harmonies.
Introduction to Post-Tonal Theory by Joseph N. Straus
A theory book that only deals with music of the early 20th century.
Books on Orchestration:
Essential Dictionary of Music by Lindsey C. Harnsberger, Essential Dictionary of Music Notation by Tom Gerou and Linda Lusk, and Essential Dictionary of Orchestration by Dave Black and Tom Gerou
Three cheap small must have books for any starting composer.
http://www.music.indiana.edu/department/composition/isfee/
An essential bookmark in your browser for orchestration. Teaches you about almost every instrument and includes videos that are activated by the space bar.
Music History (because you shouldn't write music in a vacuum)
The Enjoyment of Music (The complete edition) by Kristine Forney, Andrew Dell'Antonio, and Joseph Machlis
This will give you a brief overview of classical music's history.
Norton Anthology of Western Music (Vol. 1 & 2) by J. Peter Burkholder, Claude V. Palisca
Provides scores and history to study
The Cambridge History of Western Music Theory
More advance readings and excerpts of musical treatises written over the centuries that give you an overview of how music theory came to being.
Like I said, none of these books will teach you to compose. But for me, many of these books changed how I approached composing and thought about music. Hopefully they will do the same for you.