Footer in grdiveiw

Hi,
I have a gridview with many rows and no paging only scrollbar. I want to add a footer only for last 2 columns whose value will sum of the column(ex. total of price).I also want to make the footer fixed that is on scrolling also the footer should be visible..How can I do this...The problem is gridview is populating from database at run time.That is code for populating is writen rather than thru properties window. Please help

Thanks in advance