Saving 3 text Box values in a single Label.

Question

I am making a small project on session in asp.net. I want to save 3 text Box values in a Single Label and display it on button click.
For Example: 

             <asp:TextBox ID="txtFirstName" runat="server"></asp:TextBox>

            <asp:TextBox ID="txtMiddleName" runat="server"></asp:TextBox>

            <asp:TextBox ID="txtLastName" runat="server"></asp:TextBox>

and i want to save in Single Label.

            <asp:Label ID="lblName" runat="server"></asp:Label>

Please suggest me what should i do..