I have a website where businesses create content through a PHP backend system. Each time they create a new piece of content, I want it to publish to their Facebook pages timeline (not the users timeline).

I have created the authenticate code:

<div id="fb-root"></div>
<script>
    window.fbAsyncInit = function() {
        FB.init({
            appId      : 'XXXXXXXXXX',
            status     : true, 
            cookie     : true,
            xfbml      : true,
            oauth      : true,
        });
    };
    (function(d){
        var js, id = 'facebook-jssdk'; if (d.getElementById(id)) {return;}
        js = d.createElement('script'); js.id = id; js.async = true;
        js.src = "//connect.facebook.net/en_US/all.js";
        d.getElementsByTagName('head')[0].appendChild(js);
    }(document));
</script>
<div class="fb-login-button" scope="manage_pages">
    Login with Facebook
</div>

With manage_pages as a scope. I need to know how they can select which page they want the post to go to (if they have more than 1 page), and also how to automatically post to that pages wall when they submit the content (which is done via a PHP form).

Thanks