NavigateUrl of a hyperlink control inside FormView

how to assign navigate url of a hyperlink inside a  FormView from server side code behind

   <asp:HyperLink ID="Hyperlink1" runat="server" NavigateUrl='????????????????'                                             Target="_blank" Text='<%# Eval("DocsFe") != null ? GetFileName(Eval("DocuFe").ToString()) : "" %>'>                                          </asp:HyperLink>