facebook raffle

hello. Just wanna know what software to use if im going to give a raffle prize to those who are going to like or share our post on facebook. And i have another raffle for those who are sharing and joining our facebook event. We are giving prices to get more traffic to our forum and at the same time it will promote the product of our sponsor who gave the prizes. Any ideas? by the way we are using kunena and we are also planning for a raffle to our members but it will attract spammers so if possible we will only raffle who have around 5 posts i think. Help us please! thanks

is this impossible?