I can't find out how to PM people, I have a tab for my inbox but I can't see one for sending messages.
Click "Inbox" and there should be two options brought up - "Show All" and "Start a New Conversation". The latter option is what you want
So they aren't called PM's anymore, they are 'conversations'... After some while my eyes are adjusting to the new format, rather like walking into a Nocturnal House. E.g. initially highlights didn't seem clear but they do now.