How to display the Line Graph week wise with using one parameterise Date?

Hi,

How to display the Line Graph week wise with using one parameterise Date?

End User wants to display dates on x axis and its values on Y axis .

i.e. if  we choose 1/10/2012 then on x axis we have to display   1/10/2012    7/10/2012    14/10/2012    21/10/2012    28/10/2012      31/10/2012

suppose i select 1 parameter startdate then  other week date will startdate+7 next date will (startdate+7)+7  & next ((startdate+7)+7)+7

Please help me any one have idea.

Thanks

Nilesh Pawar