How to print six pages on one page as booklet?

I am creating a mini booklet that's over 100 pages. In Word, I made the pages 2.5" x 4". Then, I created a PDF. Now, I want to print the document as a booklet with:

1. Six pages on one piece of paper and

2. In the correct order - so page four is on the back of page three, NOT next to it.

That way, I can cut or fold the pages to bind them somehow.

Thanks for your help,

Susan