I dunno about other games, but for Galaxies you pick your race and your occupation. After you select that you can set out on adventures or quest with others to level up. It's goes basically like an old NES RPG. You lvl up, you get points, you buy new weapons, you learn new skills, you interact with other players from around the world.
However, for the games listed above, you gotta go buy the game, then pay an amount every month to play. If you wanna try out some MMORPGs without paying for a few days, you can try out:
Ragnarok Online (15 day free trial, Anime-ish 3D)
Dark Ages (10 day free trial, like Ragnarok but 2D)
Dragon Raja Malaysia (Their international server closed down so now it's Malaysia server, free the last time I played)
Planescape (Free but Java and no sound)
Mu Online (Beta, I'm trying this out right now, but it's not running smooth on my computer)
Those are just ones I've had experience with. If you want a further list,
you can get one here.