wpf datagrid multiple row deletion

Question

Hi,

    i am using a datagrid control using 3 columns first column with checkbox header as well as rows if i select header checkbox i need all the rows to be selected and  if i unselect  all the rows to be unselected  and also i have a delete button outside of the datagrid. if i check header checkbox and perform delete operation i need all the rows to be delete and if i select individual record should be delete.how to acheive this .Thanks