Go here: http://www.ecocitycraft.com/forum/conversations/add

Type their name in the "Participants" field.

 

Well, you can send them a message.
1. Scroll over the "Inbox" tab on the top right of the screen.
2. Keep the mouse over it and it should expand and say "Conversations"
3. When that pops up, the box will have "Start a new conversation" in the bottom right.
4. Click and enjoy :D

 

Or what Ryan said :D

 

No problem. :)