[otrs] Simplifying the Stats Graph.

Hi, Would you be able to give me directions on modifying the statistics shown on the Stats Graph. Currently there are too many stats shown, I only want the graph to plot stats for New Tickets, Open Tickets, Closed successful Tickets & Time Accounting? Is it also possible to increase the y-axis to get a clearer figure? What files do I need to modify? Thanks. Regards, Thau.