When your graph is done, it should look like this:
Double click on the grey area, a new window appear in which you can select to remove the shading. Always remove this shading before you print a graph. As you see in the graph above, Excel has by default chosen a light blue symbol with shadow for the data points. It is not a good choice, the points should be dark and never have such a shadow. To change this, double click on a data point, unselect shadow, and choose black for the foreground and background color of the symbol. Your graph should now look like this:
