Use
RowStyle[
^] property
<asp:GridView ID="Gridview1" runat="server">
<RowStyle HorizontalAlign="Right" />
</asp:GridView>
If you want to align particular column try this
<asp:boundfield headertext="Column1" datafield="Column1" headerstyle-horizontalalign="Right" footerstyle-horizontalalign="Right" itemstyle-horizontalalign="Right" xmlns:asp="#unknown" />
In your question you are using ItemTemplate so use CSS
<asp:label id="Label1" runat="server" text="Label1" style="text-align:right;" xmlns:asp="#unknown"></asp:label>