Match system UML

Hi.

Im going to develop match/cup page.
Like clanbase or smth, but smaller and just for one game.

First time I’m making some kind of UML diagram.

http://urgas.eu/stuff/diagram.png (picture)
http://urgas.eu/stuff/diagram.dia (gnome DIA file)

Thats part of my project. I just want to know what you think about this
diagram. I think, i made it purely wrong :).

You may give me some links about Rails and UML modeling.

Indrek.