C# Sudoku Help

[C# Programming]

Hello, I'm beginner in C# and trying to make a GUI program. I'm making a program to play Sudoku, I've few classes, some functions and interfaces but problem is I can't get how should I update my GUI. I want a program that could update GUI for every action taken within class. Is it doable without touching functions in my classes just by inheriting the main form class ?? How could I do it and what is the best way of updating a GUI from a different class. Could I pass my user control directly to update GUI.