How can I fix this code?

[Alexanderrrr]

<?php
class Post {
private $user_obj;
private $con;

public function __construct($con, $user){
$this->con = $con;
$this->user_obj = new User($con, $user);
}

public function submitPost($body, $user_to) {
$body = strip_tags($body); 
$body = mysqli_real_escape_string($this->con, $body);
$check_empty = preg_replace('/\s+/', '', $body);

if($check_empty != "") {

$date_added = date("Y-m-d H:i:s");
$added_by = $this->user_obj->getUsername();

if($user_to == $added_by) {
	$user_to = "none";
}

	$query = mysqli_query($this->con, "INSERT INTO posts VALUES('', '$body', '$added_by', '$user_to', '$date_added', 'no', 'no', '0')");
	$returned_id = mysqli_insert_id($this->con);
	$num_posts = $this->user_obj->getNumPosts();
	$num_posts++;
	$update_query = mysqli_query($this->con, "UPDATE users SET num_posts='$num_posts' WHERE username='$added_by'");

		}
	}

		public function loadPostsFriends() {
		$str = ""; //String to return 
		$data = mysqli_query($this->con, "SELECT * FROM posts WHERE deleted='no' ORDER BY id DESC");
		
		while($row = mysqli_fetch_array($data)) {
				$id = $row['id'];
				$body = $row['body'];
				$added_by = $row['added_by'];
				$date_time = $row['date_added'];

				//Prepare user_to string so it can be included even if not posted to a user
				if($row['user_to'] == "none") {
				$user_to = "";				
			}
			else {

			$user_to_obj = new User($con, $row['user_to']);			
			$user_to_name = $user_to_obj->getFirstAndLastName();
			$user_to = "to <a href='" . $row['user_to'] ."'>" . $user_to_name . "</a>";
			}
			
				//Check if user who posted, has their account closed
				$added_by_obj = new User($this->con, $added_by);	
				if($added_by_obj->isClosed()) {
					continue;
			}

			$user_details_query = mysqli_query($this->con, "SELECT first_name, last_name, profile_pic FROM users WHERE username='$added_by'");			
			$user_row = mysqli_fetch_array($user_details_query);
			$first_name = $user_row['first_name'];
			$profile_pic = $user_row['profile_pic'];

			//Timeframe		
			$date_time_now = date("Y-m-d H:i:s");
			$start_date = new DateTime($date_time); //Time of post
			$end_date = new DateTime($date_time_now); //Current time	
			$interval = $start_date->diff($end_date); //Difference between dates 	
			if($interval->y >= 1) {	
				if($interval == 1)			
					$time_message = $interval->y . " year ago"; //1 year ago
				else
					$time_message = $interval->y . " years ago"; //1+ year ago
			}
			else if ($interval-> m >= 1) {			
				if($interval->d == 0) {
					$days = " ago";				

				}
				else if($interval->d == 1) {
					$days = $interval->d . " day ago";
				}
				else {
					$days = $interval->d . " days ago";
				}
			
				if($interval->m == 1) {
					$time_message = $interval->m . " month". $days;
				}
				else {
					$time_message = $interval->m . " months". $days;
				}

			}
			else if($interval->d >= 1) {
				if($interval->d == 1) {
					$time_message = "Yesterday";
				}
				else {
					$time_message = $interval->d . " days ago";
				}
			}
			else if($interval->h >= 1) {
				if($interval->h == 1) {
					$time_message = $interval->h . " hour ago";
				}
				else {
					$time_message = $interval->h . " hours ago";
				}	
			}
			else if($interval->i >= 1) {
				if($interval->i == 1) {
					$time_message = $interval->i . " minute ago";
				}
				else {
					$time_message = $interval->i . " minutes ago";
				}	
			}
			else {
				if($interval->s < 30) {
					$time_message = "Just now";
				}
				else {
					$time_message = $interval->s . " seconds ago";
				}	
			}

			$str .= "<div class='status_post'>
					<div class='post_profile_pic'>
						<img src='$profile_pic' width='50'>
					</div>

					<div class='posted_by' style='color:#ACACAC;'>
						<a href='$added_by'> $first_name $last_name </a> $user_to &nbsp;&nbsp;&nbsp;&nbsp;$time_message				
					</div>
					<div id='post_body'>
					$body
					<br>
					</div>						

				</div>";
		
		}

		echo $str;
	
	}
}

?>

[gits]

what exactly needs to be fixed? please provide more context for the reader and ask a proper question - this will increase the probability of getting an answer to your problem.