Forms Data Controls :: Selecting Rows From A Grid View?

How do you select value from a gridview? I would like to pass values of rows selected to a query with the code below, but the grid seems to be frozen and I can't find a property for the grid that allows me to select rows.

Protected Sub GridView1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles GridView1.SelectedIndexChanged
Dim DB As New AOP29DBDataContext
If GridView1.SelectedValue = "Receiver" Then
Dim Query = From p In DB.Receivers
Select p
GridView2.DataSource = Query
GridView2.DataBind()
End If
If GridView1.SelectedValue = "Donor" Then
Dim Query = From p In DB.Donors
Select p
GridView2.DataSource = Query
GridView2.DataBind()
End If
End Sub