You don't. Years ago, urls in profiles were indeed clickable. Then pg said that they were being abused by spammers, so he removed that feature. It used to be

You don't. Years ago, urls in profiles were indeed clickable. Then pg said that they were being abused by spammers, so he removed that feature. It used to be that, if you hadn't edited your profile from before pg made the change, then your old links would remain clickable. But looking around, I see that is no longer true. So that feature is now completely gone for everybody.