Hi!
It sounds like you have a Creative Memories scrapbook, as others have noted. I'm actually an independent consultant for the company, and one of the things that they have just committed to is getting their products to the industry size - a true square of 12" x 12". However, their "older" products (anything available for purchase before this upcoming March) are actually 12" x 11.5". It's this non-square size that can cause papers bought elsewhere or CM papers that are not oriented the "right" way that will make a paper hang over the side of the page. You can trim this excess off - it's always 1/2".
The really exciting thing is that CM is going to "fix" this! So my advice is to wait to buy for new projects until March and ensure that you get enough to finish your current projects now. While the transition seems at first like a pain, it's all for the best in the end!
However, yes, the intention (although you can do it any way you like!) is for you to take the paper and affix it to the white pages inside the ablum.
In addition, you'll be able to interchange these pages with other Creative Memories albums - both before and after this project transition. (They fit in the current product line albums, which have gotten much more "exciting" and will also fit into the future, slightly larger albums - which, as a teaser, are largely solid colors, but with some new, very cute colors with great texture/sheen.)
I'm more than happy to help you over Yahoo! Messenger, on the phone, or otherwise. Please feel free to contact me if you need any help with your CM produts and projects. (I've only done three projects myself, so I'm still learning!) If you would like to check out CM products, contact me and I can send you a catalog or my website. (email is easiest for first contact: cmkristin@gmail.com)
Good luck with your project! It's such a rewarding feeling to finish a project and be able to have a book of your memories.