How did that person send you the link?
If it was through PMs, there's a red Report this PM button on the top and bottom of the PM. Click that and choose Password Phishing from the dropdown.
If the link was in a post, use the Report Post link above the post in question.
If it was in Meebo, you can only report if the conversation is still visible. There's a Dropdown arrow next to the person's avi with a report option listed. All you have to do for that one is tell why you're reporting them.