Select on the Y-axis using ur mouse and press Ctrl + F11 followed by Ctrl + G to move the window focus to Immediate window and type the following code :
selection.fill.patterned (4);
sorry no screenshot for this post :D
almost forgot, there is another way to fill the chart automatically, by installing pattern fills addins. You can find it here
References :
http://blogs.msdn.com/b/excel/archive/2007/11/16/chart-pattern-fills.aspx
http://www.andypope.info/charts/patternfills.htm
Masdel Blog 