After you get your facebook app and have added the javascript facebook api initialization code to your page (you should put it in your master template) you can use this javascript to post a link to the current page to a fan page with the specified id
postCurrentUrlToFanPage(<YOUR FAN PAGE ID>);
function postCurrentUrlToFanPage(fanpageID){
FB.getLoginStatus(function(response) {
if (response.status === 'connected') {
var uid = response.authResponse.userID;
var accessToken = response.authResponse.accessToken;
var wallPost = {
access_token: accessToken,
link: window.location.toString()
};
FB.api('/'+fanpageID+'/links', 'post', wallPost, function(response) {
if (!response || response.error) {
alert('Error occurred');
} else {
alert('Success!');
}
});
} else {
if(confirm('You were not logged in to Facebook or you need to (re)authorize. Would you like to do so now?') == true)
{
FB.login(function(){
postCurrentUrlToFanPage(fanpageID);
},{scope:'publish_stream,manage_pages'});
}
}
});
}