calender selecteddate search in gridview

very importend  !!!!!!!!!    i have a gridview with column datetime  and in this column i have datetime  allready imported on form load  from
 8:00 till 17:00
for example my datetimecolumn shows     22-5-2006 8:00
                                                            22-5-2006 8:30
how do i on calender selecteddate   search in gridview for the selecteddate
please help
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