how to include GoodReader in my list of locations on the file App

It is common to add apps to your dock, on Windows. pinning the app to the task bar, I think they call it over on Windows.

If you are referring to the Files app on iPhone or iPad (your footer here indicates Windows, so I’m unsure), apps don’t get included there, though apps can provide what Apple calls share sheets, which allow you to share (send) a file to a specific app. Whether any particular app has a share sheet, I don’t know—check with the app docs and then the vendor.