For a first time author, receiving the real live printed proof of the interior of your first book is an exciting event. First it is concrete evidence that you really have a book, and secondly it is another step closer to it being published.
This is how the process works: You receive the printed interior book proof and read through it looking for mistakes and / or changes that need to be made.
Create Space has a “change form” that you down load so you can list your changes on the form. Interior changes might be typos, forgotten paragraphs, word changes etc. Once you have listed all the changes, you upload it back to them.
You can also make design changes in the design change aspect of the process. You list those on line in the next segment. Design changes might be spacing concerns, font changes, repositioning images or even layout changes.
If your changes are more than what is allowed, you may incur an extra charge. According to Create Space policy: Additional fees will only apply to changes to trim size, margins, or body copy font size.
Actually, it is a very easy process and the only thing that takes time is reading through your book for the hundredth time, since you have probably already read it so many times before. If Create Space has any questions regarding your changes, they will contact you before making them. (I am going to guess that there will still be mistakes as this is my first time, but hey , at least it is almost ready to be published.)
After they review and make your requested changes, you can opt for a digital copy or a printed copy. Once you approve your book, you receive a complete (with cover) printed copy for your final approval before your book is published. What could be simpler? I love this process!
Mt McKinley 
Sharron Grodzinsky Author 