I found an interesting application on TkDocs that acts as a simple feet to meters converter and poked around at it.

While it isn’t choosing a file using a popup, it does provide some examples of integral concepts to using Tkinter. These include setting up a grid to place the widgets (buttons, text boxes,ect ) on, use of function calls within a window, applying UI rules dynamically.
To elaborate on the last point this program includes a 2 line snippet that adds vertical and horizontal spacing to all of the widgets within the main window.

While I’m sure I have more to learn, once I learn how to make a UI to select a file in Tk, the next thing to do would be making a proper list of project goals for the alphastat program.