The file that you are opening is a book document, which is simply a container for holding Indesign files. They are used in long documents, for example each chapter might be a separate Indesign document and the book file is used to hold the whole thing together (as well as many other features).
A book document should have the extension .indb, whereas an actual Indesign file has the extension .indd.
Apparently you need to create a normal InDesign document, simply go to File > New > Document
Well, rats. That stinks. But, thanks for the info. I guess I have to suck it up and start from nothing, because that's all I could find. Thank you!