Create a polynomial from divided difference table

Here is what i need to do. I need to have the user input and interval, the number of interpolation points (3 < n < 25), and the function to interpolate. Then i need to create a divided difference table, then I need to display the error by im assuming plotting the original function against the interpolated function. I have everything working up to the error part. What i need help with is, I need to construct the polynomial from the divided difference table, which would not be difficult if there were a set number of interpolation points, but the user can put in any amount up to 24. so how can i create a polynomial, so that any number of interpolation points i can that function so I can graph it?