My actual question is: what can we do more about this kind of things in order to improve the quality of the website? It does not look like voting and trying to close questions is enough but rather maybe we need that the actual real users are more educated in regards to what they have to do?
Iain and Sven have pointed out the big picture problems and why there might not be anything we can do about the non-professional questions.
However, if you want to try to do something, voting and closing are the best tools you have available... and you could use them more. (Please don't take the following too seriously or personally, I've made it about you and exaggerated a bit for effect only.)
Crappy questions that are downvoted and have no answers will get automatically deleted. And questions that are at -2 (or worse) are a much better indication that crappy questions aren't wanted than ones that sit at 0. You've only voted 81 times in total - less than I've voted in the last 3 days! Get out there, click the down arrow on every crappy question you see and move then move on.
Closing and reviewing
Although downvoted questions don't have to be closed to be automatically deleted, closing them prevents answers from being posted and makes it even clearer that they're crappy. I can't see how many times you've voted to close, but I only see 5 close-vote reviews in your profile. Everyone else who's posted on this thread has done a fair amount of closing and reviewing, it's your turn! (For bonus marks, do what I do and click through to the actual question when you're reviewing close-votes, downvote the ones that deserve it, then go back and finish the review.)
As for the rest of you...
Feel free to downvote more often, too.