UO Second Age

I cant for the life of me understand what to do once i start.
I boringly wander round towns trying to understand whats what.where to start a quest Etc.
Is there Any guides or help i can get?

I just started on the server and i found that the ninja/samurai/necromancer/paladin classes are all unavailable to play
Why is this?
are just not allowed on the server? or do i need to patch or something

thanks =D