Now, how do I include these files into the package?

What do you mean by "the package"? Do you mean that you want to have these files bundled up with your .pm files into a distribution so that if your module is installed somewhere, the files come along with it and your module can find them automatically?

If that's what you want, then you need to include instructions to that effect in your Makefile.PL or Build.PL so that those files are installed in your Perl library path. By default, only .pm and .pod files are actually installed. For example, here's a recipe from the Module::Build::Cookbook:

Adding new file types to the build process
  Sometimes you might have extra types of files that you want to insta
+ll
  alongside the standard types like .pm and .pod files. For instance, 
+you
  might have a Bar.dat file containing some data related to the "Foo::
+Bar"
  module. Assuming the data doesn't need to be created on the fly, the
  best place for it to end up is probably as Foo/Bar.dat somewhere in
  perl's @INC path so "Foo::Bar" can access it easily at runtime. The
  following code from a sample "Build.PL" file demonstrates how to
  accomplish this:
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