You can use any type or size of book as long as it is a hardback.
Section off the first pages of your book, from the very first blank page to the first page of the story.
Take the section and fold it in to where the body of the text ends on the right side of the page. You will continue to fold the pages to this side of the text block to ensure that all of the folded pages will be the same length.
Once you have evenly positioned the edge of the page to the right side of the text, crease the pages down so that they will stay folded.
Now that the first section of pages are folded, separate the section into groups of two pages and then fold the separate groups of two back over (if there are an odd number of pages within the section that's ok, just take the thickest first page and fold it back over by itself). This separation of the first section of pages is so the first fold isn't larger than the rest.
Now that the first section of introduction pages are done, you can begin folding the rest of the pages by twos, folding them to the right side of the text block each time.
About halfway through the books arch should be taking form.
Then when you have folded each of the pages by twos the book should look something like this. Note: Right after the last of the pages have been folded the arch may not lay perfectly flat against the spine. This is no reason to be concerned, the pages will soon fall onto place.