"Initial x-value" and "Final x-value" - The function does not need to span the entire graph. It is possible to create a piecewise function by defining the x-values over which each function is to be shown.
"Label on Plot" - To label the background function (for example, as "parabola"), enter it here.
"Color" - To change the color of the background function, enter the hex code for that color here. The default is 000000 (black). It is recommended to choose a color other than green, since it is easily confused with being the answer.