Here the specific terms you should be concerned with, read these carefully:
Promotions on Facebook must be administered within Apps on Facebook.com, either on a Canvas Page or a Page App.
You must not condition registration or entry upon the user taking any action using any Facebook features or functionality other than liking a Page, checking in to a Place, or connecting to your app. For example, you must not condition registration or entry upon the user liking a Wall post, or commenting or uploading a photo on a Wall.
You must not use Facebook features or functionality as a promotion’s registration or entry mechanism. For example, the act of liking a Page or checking in to a Place cannot automatically register or enter a promotion participant.
You must not use Facebook features or functionality, such as the Like button, as a voting mechanism for a promotion.
You must not notify winners through Facebook, such as through Facebook messages, chat, or posts on profiles (timelines) or Pages.
You can read the specific terms of running promotions on Facebook right here, https://www.facebook.com/page_guidelines.php
You need to use a third party Facebook app designed for contests. Here is a list of third party Facebook apps that you can use for contests. These were posted by Andrea Vahl:
- Wildfire – easy to set up and can be as little as $50/week.
- North Social – also easy to set up they charge per month and based on how many fans your page has – good rates.
- Votigo – they currently focus on larger scale campaigns and can be very customized to your needs. (Update: now they have self-service options)
- Fanappz – I have not personally tried them but Bob Saget uses their quiz application.
- Strutta – Great for photo, video or essay contests with a professional look and great features. The pricing starts at $299 but it’s gorgeous.
- ShortStack - This is a great app for creating all kinds of custom tabs and they have a sweepstakes entry widget that you can add. The drag-and-drop interface makes it easy to create your entry form.
- Woobox – Another low-cost sweepstakes application that is easy to set up yourself.
- Offerpop – This sweepstakes application is free for Pages with 100 Likes or less.
- EasyPromos – Your first contest is free
Just because you see someone else breaking these rules does not mean you should. You risk having your page suspended, is it worth the risk?