registration.php

<html lang="en">
	<head>
		<title>Registration</title>
		<link rel="stylesheet" type="text/css" href="css/style.css">
		<link href='http://fonts.googleapis.com/css?family=Muli' rel='stylesheet' type='text/css'>
	</head>

	<body>

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

		<div class="register">
			<h1>Registration</h1>

			<form name="registration" action="register.php" method="POST">
				<label for 'username'>Username: </label>
					<br>
				<input type="text" name="username"/>
					<br>
				<label for 'password'>Password: </label>
					<br>
				<input type="password" name="password"/>
					<br>
				<label for 'first_name'>First name: </label>
					<br>
				<input type="text" name="first_name"/>
					<br>
				<label for 'surname'>Surname: </label>
					<br>
				<input type="text" name="surname"/>
					<br>
				<label for 'address'>Address: </label>
					<br>
				<input type="text" name="address"/>
					<br>
				<label for 'email'>Email: </label>
					<br>
				<input type="text" name="email"/>
					<br><br>
				<button type="submit">Submit</button>
			</form>
		</div>

		<?php
			} else {

				$user = 'root';
				$pass = '';
				$db = new PDO( 'mysql:host=localhost;dbname=users', $user, $pass );

				$form = $_POST;
				$username = $form['username'];
				$password = $form['password'];
				$first_name = $form['first_name'];
				$surname = $form['surname'];
				$address = $form['address'];
				$email = $form['email'];

				$sql = "INSERT INTO users ( username, password, first_name, surname, address, email )
				VALUES ( :username, :password, :first_name, :surname, :address, :email )";

				$query = $db->prepare( $sql );
				$query->execute( array( ':username'=>$username, ':password'=>$password, ':first_name'=>$first_name, ':surname'=>$surname, ':address'=>$address, ':email'=>$email ) );

			}
		?>

	</body>
</html>