Thank God. For almost 1 week, I already get the answer
the only problem is the authorization. If you try to follow the code of this tutorial http://www.sitepoint.com/creating-a-php-oauth-server/. You create a login.php for authorization. Here's the code of mine.
The only problem is the form. You need to name the submit button 'allow' and then form action. See my form there is " action="">". The tutorial don't have this code. It will give you error for request token If you don't have oauth_token and oauth_callback in your form inside the action.
I hope it will help you.