用php登录后在主页面进行更改

Question

I have already made registration and login pages for my web page. The question is that I want to display the name and the image of the user after login, in other words, I want to make some changes in my main page after login. So this is my code:
lib.php

 function checkUser($username,$password){
   include "connection.php";
   $result = mysqli_query($conn, "SELECT * FROM `data` WHERE `username` = '$username' AND `password` = '$password'") or die("No result".mysqli_error());

    $row = mysqli_fetch_array($result);
    $logic = false;

    if (($row['username'] == $username) && ($row['password'] == $password)) {
        echo "Login is successfull. Welcome <b>".$row['username']."</b>";
        $logic = true;
    }
    else{
        echo "Failed to login. Username or password is incorrect. Try again.";
    }
    return $logic;  
}
function logIn($username, $password){
    include ("connection.php");
    $_SESSION["loggedInUser"] = $username;
    $_SESSION["loggedInTime"] = time();
}

action.php

<?php       
  include "lib.php";

  if(checkUser($username,$password)){
    logIn($username, $password);
    header("Location: index_en.php");//goes to my main page
?>
    <li><a href="#">Hello, <?php echo $username; ?></a></li>
    <script type="text/javascript" src="js/jquery-1.10.2.min.js"></script>
    <script type="text/javascript">
      console.log("successfull");
      $(".nav_header").remove();//I tried to change my index_en.php page, but no changes appear there
    </script>
<?php
    }
?>

Answer 1

As I understood the question, so I think your code might be like this,

action.php

<?php       
  include "lib.php";

  if(checkUser($username,$password)){
    logIn($username, $password);
    header("Location: index_en.php");//goes to my main page
?>
    <li><a href="#">Hello, <?php echo $username; ?></a></li>
    <script type="text/javascript" src="js/jquery-1.10.2.min.js"></script>
    <script type="text/javascript">
      console.log("successfull");
      $(".nav_header").remove();//I tried to change my index_en.php page, but no changes appear there
    </script>
<?php
    }
?>

As, you want some change in Index_en.php(Home Page) when user is already logged in, your page should contain,
index_en.php

<?php
session_start();
if(isset($_SESSION['username'])){
   echo "Hello, ".$_SESSION['username'];
}
?>