Master Page Insertion in ASP.NET

%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
This is first<br/>
    <a href="Default2.aspx">Default2.aspx</a>
<a href="Default3.aspx">Default3.aspx</a>
</asp:Content>