How do I make a GUI to give input to my board from the computer? (Beginner)

Hi
I'm trying to make a pulse sequence generator. The user should be able to change some variables (for controlling frequency, pulse width, etc.) within the code without having to reprogram the board every time a variable changes. I realize that this can be done through serial monitor, but I need a graphical user interface that looks like this:

How do I make something like this and how do I interface it with Arduino?
By the way, I'm new to Arduino. I have some background in C and I have never done anything graphical.
Thank you in advance.

I presume your intention is that the GUI will be on your PC and, if so, you need to get advice about that from a Forum that deals with PC programming. If you use Windows (I don't) the various Visual XXX programming languages should make it easy to create a GUI.

As far as sending data to the Arduino is concerned have a look at the examples in Serial Input Basics - simple reliable ways to receive data.

The technique in the 3rd example will be the most reliable.

You can send data in a compatible format with code like this. It will be possible to create equivalent code in any PC programming language.

Serial.print('<'); // start marker
Serial.print(value1);
Serial.print(','); // comma separator
Serial.print(value2);
Serial.println('>'); // end marker

...R