我是用PHP Mysql实现登录的，怎样在登陆后由登陆界面跳转到index.html主页面并在登陆的地方显示用户名

index代码：<nav class="menu">
<a class="menu__item" href="dlzc.html"><span>Login</span></a>
<a class="menu__item menu__item--current" href="#"><span>About</span></a>
<a class="menu__item" href="#"><span>Contact</span></a>
</nav>
登陆代码：<?php
session_start();
$con=mysql_connect("127.0.0.1:3306","root","");
mysql_select_db("yilanchehua",$con);
if(mysqli_connect_errno($con)){
echo "连接 MySQL 失败: " . mysqli_connect_error();
exit();
}
$uuser=$_POST['User'];
$ppassword=$_POST['Password'];
$sql="select User,Password from newuser where User='$uuser' and Password='$ppassword'";
$result=mysql_query($sql);
$num=mysql_num_rows($result);
if($num){
$row=mysql_fetch_array($result);
echo $_SESSION["username"]=$uuser;
//应该是改这里吧
}
else{
echo "<script>alert('用户名或密码不正确！');history.go(-1);</script>";
}
mysql_close();
?>

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