Display output into a text box in a GUI

I am working on a project for a class that requires us to make a GUI. We have to incorporate Curve fitting code and Gaussian elimination code into our GUI that will pull an excel file and use the data to produce results. Right now, we are stuck on trying to display an output value from our Gaussian elimination code into a text box inside the GUI. Our professor is not currently available to help so our group has literally no Idea what to do right now. Basically, we have to pull data from both curve fitting and Gaussian elimination code from an excel file and then display the results inside the GUI with a graph and stuff. Any help would be greatly appreciated as we have no idea what we are doing.

[Jan]

It would be easier to answer if you ask a specific question. What is the next step you want to solve? What have you done so far?