While the title should tell you what the question here is, let me just clarify here. I wish for someone to tell me how to invite a fellow player. If I go to "Casual Game" on the multiplayer screen, an extra window appears where I can pick a board on the left, and (optionally) choose an opponent on the right. When I click on a player's nickname, however, jack squat happens. So can anyone fill me in on how this works? That'd be mighty fine
After you click their name, click "create game" (bottom right). If they accept the invite the game will begin.
Once you click a person's name, you have to hit the "Create Game" button in the bottom-right of the screen. If your screen is too small, it may not show up unless in fullscreen, or maybe not even then. After creating a game, the person you invite has to accept the invitation. If you didn't select a person to invite, it will appear in the casual game section at the bottom of the screen until someone click on it and they will play with you.