Ok, I'll give the definitive answer --
The reputation score starts out at 10 for every new member. When someone "upvotes" your post, you get 1 reputation point. When someone "downvotes" your post, you lose 1/3 of 1 point.
The little "thumbs up" and "thumbs down" smilie appears at the top of every post.
If you want to see more posts like this, click the Thumbs Up.
If you don't like the post, click the Thumbs Down.
PLEASE NOTE: You are NOT voting for what you think of the information. If someone posted a news article about Bishop Williamson being put on trial in Germany, I would certainly up-vote the post -- saying "thanks for the information!" -- even though I would be VERY UNHAPPY about +W being put on trial. Long story short, Don't shoot the messenger. It hurts his/her reputation score if you downvote.
A few other things to note:
1. The more you post, the higher your rep score is likely to be (unless you GROSSLY don't fit in here).
2. It's worthwhile to post in controversial threads, even when they're divided 50/50. Fans of your position will up-vote you, and "the other side" will likely downvote you. But 10 UP and 10 DOWN does *not* equal zero. You would net 7 points. (See above: a down-vote only costs you 1/3 of a point!)
3. By up-voting and down-voting, you help to encourage the kind of posts you'd like to see on CathInfo. Don't let all the OTHER people vote for what they want -- let your voice be heard! Unlike the U.S. national elections, your vote actually DOES matter here. We're a pretty small group.