Locating a Facebook page id is easy
While viewing a Facebook page, look at the URL in the address bar at the top of the browser window. For a Facebook page with a URL like:
the page id is linktofb.
the page id is 1234567890.
the page id is 123654123654123.
Make sure you are viewing a Facebook page and not a Facebook profile; a page has "Likes", a profile has "Friends". To create a page while viewing your profile, select "Create Page" from the pull-down menu in the upper right corner of the screen. Be sure your page is not a group. A group may restrict access to members.