How do i downvote a comment?

You can't until you've been here long enough. Its a troll account control mechanism. Just give it time.

You got have a account opened and participate on here often and then they give you the downvote but they done away with it for new accounts cause too many people was abusing the feature.

I'm new too. They don't want us down voting the idiots right off the bat. Oldfags need to feel good about themselves.