The process is simple - you just adjust your pledge with the additional cost of each book.
Volume 1 is $25.
Volume 2 is $30.
For every additional book, just increase your pledge to add the cost of the book you wish to purchase, and send me a message so I can note in your backer info which one(s) you chose. We would appreciate if you could also include additional shipping (about $3-5 per book).
Don't see the answer to your question? Ask the project creator directly.