How is it possible that people can make so fantastatics graphics like this
http://unity3d.com/images/promos/game-list2.jpg
then i am trying to make something nice, it is just some cubes, that is all…
Is it all about training?
Not all, but most. It is art.
Yeah run through as many tutorials as you can… of course a lot of it is texture work as well.
Start with the basics and jsut work your way up 
Okay Thank you.:
I have allways tried to make a succesful game, but i allways get stuck while programming… Because i would like to get into the android/App store marked, and see if have any luck to be a game developer
Any advice?
And also learn witch script you like and also learn Shader scripts to cause that helps a lot also that first game didnt look that hard with texturing
and also it depends on which kind of game you are creating FPS, TPS, or Sky View play
But it does take time lots and lots of time
Learning art principles is far from easy, if you’re truly serious about this then it will take years.
Yup… it takes years…if you want smooth graphics, you will need patience, practise…and perseverance. Tutorials will only get you so far… practise anatomy, drawing… learn about graphics… programming… and most of all PRACTISE
It takes 12 years to master any subject but that does not mean you can’t make anything good in the mean time. Stick with your cubes make sure the programing is right before you start on any art of graphical work. When your game play is how you want it slowly work on each part of the games graphics till you reach the level you want for each, even if it means getting outside help.