Ultimate Facebook set up

Within the Autopost section of the set-up screen it says

"Choose the Facebook user ID from the user box, or leave selection to "Me" to use your own profile. Remember, the plugin needs to be granted extended permissions to access the profile. To allow posting to a fan page, you need to be administrator of that page. Also, extended permissions will have to be granted, too"

I can't seem to find where to put in that user id for my facebook page in order to direct the autoposts there?

James