yeah if you want to do two separate plots, then do
subplot(rows,columns,number)
so like, subplot(2,2,1) creates a single figure with 2x2 plots, i believe subplot one is the top left, you do the next one as subplot(2,2,2), and so on
if you want to do two functions on the same plot, then use "hold on", e.g.
plot(x,y1)
hold on;
plot(x,y2)
hold off;
grid;