Registration page (Write to DB)

        <?php
            if(empty( $_POST ) ) {
        ?>

        <div id="reg_form" style="background-color: #e6e6e6;">
            <h1 style="font-weight: bold; text-align: center;">Register an account</h1><br>

            <form name="registeraccount" method="POST">
                <label for 'firstname'>First name: </label><br>
                <input type="text" name="firstname" placeholder="First Name" reqiured/>
                    <br>
                <label for 'lastname'>Last Name: </label><br>
                <input type="text" name="lastname" placeholder="Last Name" required/>
                    <br>
                <label for 'username'>Username: </label><br>
                <input type="text" name="username" placeholder="Username" required/>
                    <br>
                <label for 'password'>Password: </label><br>
                <input type="password" name="password" placeholder="Password" required/>
                    <br>
                <label for 'email'>Email Address: </label><br>
                <input type="email" name="email" placeholder="Email Address" required/>
                    <br><br>
                <button type="submit">Register account</button><br><br>
            </form>
        </div>

        <?php
            } else {
                $servername = "198.71.225.55:3306";
                $username = "";
                $password = "";
                $dbname = "heartfx_users";
                $db = new PDO( 'mysql:host=198.71.225.55:3306;dbname=heartfx_users', $username, $password );

                $form = $_POST;
                $firstname = $form['firstname'];
                $lastname = $form['lastname'];
                $username = $form['username'];
                $password = $form['password'];
                $email = $form['email'];

                $sql = "INSERT INTO Users ( firstname, lastname, username, password, email )
                VALUES ( :firstname, :lastname, :username, :password, :email )";

                $query = $db->prepare( $sql );
                $result = $query->execute( array( ':firstname'=>$firstname, ':lastname'=>$lastname, ':username'=>$username, ':password'=>$password, ':email'=>$email ) );
            }
        ?>