The function f(x) and its domain are given in the control panel. There are two red hotpots in the "Domain and range" window that can be moved along the x-axis. These two points are used to specify a green domain, whose image under f(x) is shown in magenta. To view the range in the "f(x)" window, click the "Range" checkbox in the control panel.  This will display the range of the function along the y-axis in magenta.  To view the function graph in the "f(x)" window, click the "Graph" checkbox.  This will display the function in white, with the function over the specified domain shown in green.