Help me for this Problem please

Question

Hi All,
I am Narasima.plz any body Hlp me for thsi Proble.Now i am new for the WPF .net 3.5.
i am developing the POS(Point of sales in WPF) i have Tabcontrol this Tabcontrol can have Three Tabpages like Customer,Itemes,Payment,when ever i press the F2 it display the customer tabpage and same like a F3 for Itemes,F4 for Payments now i am doing like this but i am not get in plz help me .it is very Urgent .we rae using Devexpress grid 8.3 calculations in grid,once scan the Bar code It will be Automatically get the price and how much the vat and every thing.
Thanks,
narasima