Boy, am I dense.

I see two "depends" lines in Reading.cabal:

pkgconfig-depends:
&
build-depends: base -any

I uncommented out

import qualified Data.Map as M

and looked at Lekah's message:
src\Main.hs:19:17:

   Could not find module `Data.Map':
     It is a member of the hidden package `containers-0.3.0.0'.
     Perhaps you need to add `containers' to the build-depends in
your .cabal file.
     Use -v to see a list of the files searched for.

So I put "containers" after one of the depends:
build-depends: containers base -any

Leksah said:
Setup: .\Reading.cabal has been changed, please re-configure.
=========================================
Setup: Reading.cabal:9: Parse of field 'build-depends' failed.
=========================================
Can't activate package C:\Documents and Settings\brazee\My Documents
\Code\Windows\Reading\Reading.cabal: 9: user error (Parse of field
'build-depends' failed.)
Can't read package file

So I undid that change and did this instead:
pkgconfig-depends: containers

I got the following:
Can't read package file
Setup: .\Reading.cabal has been changed, please re-configure.
=========================================
Configuring Reading-0.0.1...
Setup: pkg-config version >=0.9.0 is required but it could not be
found.
=========================================
The job now runs with these unused imports.

I never found "build-depends" in my cabal file.

I edited this with ultra-edit as I know how to get to it.

I'm still clueless about what I did, despite being told by two
different people what to do and not being able to follow the
directions, but doing trial and error instead.   Even after I
finished, I don't understand the directions.