C program for solving Runge-Kutta 4th order

I'm working on simple project on my university, and I need C programmer who will made me a program that solves Runge-Kutta 4th order for 2D harmonic oscilator. Program needs to calculate the order for given inputs, show the results, write them in file that can be opened with simple text editor, and show the results on the graph. On the linux is excellent program to make graphs that is called Grace, but this program will work on Windows and its your choice how you will implement that part... Equation is in the picture... For any kind of question, feel free to ask me...