How to pm another member?

Can anybody tell me how I send a pm to another member please?
It's not quite personal messaging, but you can click on a user's name to view their information page. Unless a user has disabled it, there should be a contact link towards the top to the right of their username. This sends an email from the email address you used when you registered for the site, so the person you're contacting will of course then get your email address.