passing sort expression and direction parameters in pagination method

In Markup set GridView attributes as given bellow

AllowSorting="True" 
OnSorting="gridView_Sorting"

For each column Header Template do the following

<asp:TemplateField SortExpression="YourFieldName">
     <HeaderTemplate>
<asp:LinkButton ID="linkbutton" runat="server" Width="100%"                                        CommandName="Sort" CommandArgument=" YourFieldName" />
     </HeaderTemplate>
     <ItemTemplate></ItemTemplate?                 
</asp:TemplateField>

And

In code behind gridview_Sorting event handler
Use e.SortExpression and e.SortDirection to further implement the logic.

HTH