If you don't need to edit items in the PDF, you can just place it on an InDesign page and add more pages, etc. But you cannot change it.
To convert it so that PDF elements are editable in InDesign, you'll need to use a tool that converts the PDF to an InDesign document. One example is PDF2ID from Recosoft. http://www.recosoft.com/products/pdf2id/
Hope this helps!
There is also PDF2DTP from Markzware: http://www.markzware.com/products/pdf2dtp
I work for Markzware, just to be clear. Coming directly from the Adobe world and graphic design/prepress, gives us an advantage on the overall quality of the PDF to InDesign conversion. Hear similar right from an InDesign user and operator of both PDF2ID from Recosoft and PDF2DTP from Markzware:
Hello Sara -
I represent Recosoft, the makers of PDF2ID. PDF2ID supports InDesign CS4 through CC. You can visit our web site at http://www.recosoft.com and obtain a trial of PDF2ID. We also have some excellent video tutorials available on Youtube (I've included one link below). We have excellent recommendations by InDesign Secrets. PDF2ID v4.0 recently received a 4.5 out of 5 stars rating in the April 2014 Photoshop Users Magazine.