I believe you need 2 karma to post links (to avoid bots probably). I've upvoted your comment so I think you'll be able to post links now.

You just go to "submit," type in the title you'd like your post to have, then paste the link in the link field. Clicking up arrows gives karma, i believe. It also saves stories (if you go to your profile, you can click on 'saved stories' or something like that and see links you've saved)