My Code

<?php include ( "inc/header.php" ) ?>
<?
$reg = @$_POST['reg'];
//declaring variables to prevent errors
$fn = ""; //First Name
$ln = ""; //Last Name
$un = ""; //Username
$em = ""; //Email
$em2 = ""; //Email 2
$pswd = ""; //Password
$pswd2 = ""; // Password 2
$d = ""; // Sign up Date
$u_check = ""; // Check if username exists
//registration form
$fn = strip_tags(@$_POST['fname']);
$ln = strip_tags(@$_POST['lname']);
$un = strip_tags(@$_POST['uname']);
$em = strip_tags(@$_POST['email']);
$em2 = strip_tags(@$_POST['email2']);
$pswd = strip_tags(@$_POST['password']);
$pswd2 = strip_tags(@$_POST['password2']);
$d = date("Y-m-d"); // Year - Month - Day

if ($reg) {
if ($em==$em2) {
// Check if user already exists
$u_check = mysqli_query("SELECT username FROM users WHERE username='$un'");
// Count the amount of rows where username = $un
$check = mysqli_num_rows($u_check);
//Check whether Email already exists in the database
$e_check = mysqli_query("SELECT email FROM users WHERE email='$em'");
//Count the number of rows returned
$email_check = mysqli_num_rows($e_check);
if ($check == 0) {
  if ($email_check == 0) {
//check all of the fields have been filed in
if ($fn&&$ln&&$un&&$em&&$em2&&$pswd&&$pswd2) {
// check that passwords match
if ($pswd==$pswd2) {
// check the maximum length of username/first name/last name does not exceed 25 characters
if (strlen($un)>25||strlen($fn)>25||strlen($ln)>25) {
echo "The maximum limit for username/first name/last name is 25 characters!";
}
else
{
// check the maximum length of password does not exceed 25 characters and is not less than 5 characters
if (strlen($pswd)>30||strlen($pswd)<5) {
echo "Your password must be between 5 and 30 characters long!";
}
else
{
//encrypt password and password 2 using md5 before sending to database
$pswd = md5($pswd);
$pswd2 = md5($pswd2);
$query = mysqli_query("INSERT INTO users VALUES ('','$un','$fn','$ln','$em','$pswd','$d','0','Write something about yourself.','','','no')");
die("<h2>Welcome to the HoogleyBoogley Network</h2>Login to your account to get started ...");
}
}
}
else {
echo "Your passwords don't match!";
}
}
else
{
echo "Please fill in all of the fields";
}
}
else
{
 echo "Sorry, but it looks like someone has already used that email!";
}
}
else
{
echo "Username already taken ...";
}
}
else {
echo "Your E-mails don't match!";
}
}
?>
    <div class="container">
        <div id="home_login">
            <table>
                <tr>
                    <td width="60%" valign="top">
                        <h2>Join Us Today!</h2>
                    </td>
                    <td width="40%" valign="top">
                        <h2>Sign Up Now!</h2>
                        <form action="#" method="post">
                            <input type="text" name="fname" size="25" placeholder="First Name"><br /><br />
                            <input type="text" name="lname" size="25" placeholder="Last Name"><br /><br />
                            <input type="text" name="uname" size="25" placeholder="Username"><br /><br />
                            <input type="text" name="email" size="25" placeholder="Email Address"><br /><br />
                            <input type="text" name="email2" size="25" placeholder="Comfirm Email Address"><br /><br />
                            <input type="text" name="password" size="25" placeholder="Password"><br /><br />
                            <input type="text" name="password2" size="25" placeholder="Comfirm Password"><br /><br />
                            <input type="submit" name="reg" value="Sign Up" id="home_signup">
                        </form>
                    </td>
                </tr>
            </table>
        </div>
    </div>
<?php include ( "inc/footer.php" ) ?>