Question: I want to develop facebook applications and I have bought some books from amazon. But this books contents are for old facebook APIs. (2008-2009).
Can I develop applications with old api? Or I have to use new version?

Answer: 
You can still use the old api's, but as you can probably imagine it is discouraged. Read more in the [facebook developer documentation](http://developers.facebook.com/docs/).

**EDIT**
Given your name, I assume that you know a bit of php. To get started just go to <http://www.facebook.com/developers> and create a new application. Facebook then presents you with the following tutorial, that I think you should be able to follow:

> 
> Step 1: Download Facebook's PHP Library
> 
> 
> Extract this archive into a directory on your hosting server where you can host and run PHP code:
> 
> 
> 

```
$ curl -L http://github.com/facebook/php-sdk/tarball/master | tar xvz
$ mv facebook-php-sdk-* facebook-php-sdk
$ cp facebook-php-sdk/examples/example.php index.php

```

> 
> Step 2: Replace the IDs in index.php to have your own app information
> 
> 
> It should look like this when you're done:
> 
> 
> 

```
<?php
// Awesome Facebook Application
// 
// Name: YourAppName
// 

require_once 'facebook-php-sdk/src/facebook.php';

// Create our Application instance.
$facebook = new Facebook(array(
  'appId'  => 'CHANGE_TO_YOUR_OWN_APP_ID',
  'secret' => 'CHANGE_TO_YOUR_OWN_SECRET',
  'cookie' => true,
));

```
I would definitely not start a new app with the old APIs. Facebook has deprecated many of the old APIs and is in the process of deprecating the rest of them. Additionally, the authentication system changed completely about 6 months ago. Sorry for the bad news but books on Facebook that are more than about 3-6 months old are basically worthless at this point.