Basically TNGv2 is just three files. An executable and two libraries. This doesn't mean that no other files are created later.

Setup will install these three files and subfolders:
Doc - here are user manuals
Lang - here are localization files for other languages
Samples - here are sample g-code files
Profiles - this folder contains profile folders which contain all your settings/scripts/configurations,...

Profiles folder is an interesting one. Upon first application start new empty profile named <Default> will be created with two files:
Settings.settings - this is main settings file
Keys.txt - this file contains keyboard shortcuts definitions

Other files used by software are also stored here. Most common are:
License.lic - this is license file
Parameters.txt - this files contains persistent parameters. Persistent parameters keep their value between restarts.
ToolTable.txt - this is tool table file. It contains information about your tools.
CoordinateSystem.txt - this is coordinate systems table file. It contains information about your coordinate systems.

Custom toolbar buttons are defined in files named:

Custom 'State' tabs are defined in files named:

Configuration for USB extension modules are in file:

Expression evaluator configuration is in file:

There are also some folders in your profile folder:
Scripts - here are all scripts that override default software behavior
UserCmd - here are your custom commands written as g-code or python script
UserGen - here are your g-code generators written as g-code or python script

Each of these additional features deserve its own explanation and tutorial which we will create.