VGA Calculator Display using VHDL

I’m working on a floating-point calculator in VHDL for my Altera DE2 board, and I want it to display on a VGA monitor with functions like Add, Subtract, Multiply, Divide, and Exponents. I’ve already set up a VGA controller, but I’m struggling with how to effectively display the calculator interface on screen especially how to use a buffer for pixel data. Could you explain with an example of how to implement this? Also, once I understand the display logic, I eventually want to extend it toward practical tools like a price bond calculator where users can enter values and see results directly on the VGA screen.