Run your first file first (Full Install). Pay attention to where you are going to install Realtracks and Realdrums in the opening install screens. They'll require quite a bit of hard drive space. It would also make sense to install the Realtracks before installing any shots or holds or patches.
If you click the support tab and go to BiaB 2012 FAQ you can search for 'install' and read it all.
Part of it is below -
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With Band-in-a-Box DVD's, you'll also need to choose your RealDrums and RealTracks folder locations. These are the folders where the 'Drums' and 'RealTracks' subfolders are located. It is normally best to choose your Band-in-a-Box folder (i.e. C:\bb) for these, although you may have previously installed them somewhere else, for example on another hard drive with more space for the large audio files. The installer should normally be able to locate your Drums and RealTracks folders automatically, however in some cases it cannot, for example if you had manually copied and pasted the folders to a new custom location rather than installing them there.

With upgrades that you downloaded or got on CD (rather than DVD), you'll have separate installers for the RealDrums and RealTracks. The same information applies to these, except that you won't be selecting your Drums and RealTracks folders when you install Band-in-a-Box itself.

Note that if you want your RealTracks files located in C:\bb\RealTracks, you select C:\bb as the RealTracks folder location, and similar with the Drums.
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