Everything you need to practice is on this site. The thirty codes, a deep reading of each one, and the four passes are published in full and always will be.
The book is why it works. It sets out the architecture the codes are built on: polarity and the three axes, the seven limiting beliefs, the over- and under-compensations that grow from them, the syntax rules the lines are shaped by, and the ninety-day arc.
Harmonic Linguistics: Self-Guided Polarity Integration Through Language is available in paperback and for Kindle. The companion workbook gives the ninety days a written container: every code laid out for each day, with space to handwrite each line and room for notes.
The book runs to seventeen chapters. It covers polarity and the three axes, the seven limiting beliefs and the over- and under-compensations that grow from them, the syntax rules the codes are built on, the four-pass delivery method, a week-by-week map of the ninety days, guidance on resistance and emotional surfacing, and a deep reading of every code.