How to create the effect of height in a map.
To explain better, how do you create the effect of depth, as what you see in the enormous rooms of the game? That effect which I think is done with the fog_controller.
http://it.tinypic.com/r/2rotiqd/8
I tried creating a huge block that enclose my map, but compile times (portalflow) are infinite.
I also tried to see the maps already created by the valve; There are blocks with the trigger, with hints and nodraw. But I do not know how to do. When I try to do something I always marks a leak.
I'm Italian and I hope I explained as best as possible. 
Thats the only entity you'll need. 
In the screenshot thats just a model and a fog_controller, with the right proberties you could get the same effect.
yes, I have to add the fog_controller and some prop_static. But I also have to close the whole in a large block, to avoid leaks. The problem is that if I create a huge block with a textured floor,compile times of vvis (portalflow) are very long. How do I not let him render the large block without causing leaks?
That's always a hard question. It's called optimization.
Vvis generally should be done in a breeze.
I HIGHLY recommend reading all this carefully:
http://www.optimization.interlopers.net/
It gives a very good overview of what optimization is, and what it does.
The most important thing to remember in portal 2 mapping:
If it doesn't really block your line-of-sight; make it a func_detail.
That should make your compiles a lot faster!
The problem with fog, is that it needs an open space, so it it gets to the max at 5000 distance, and you need the feel that where you look there is unlimited space, you cant just box around a very small area, because then the box's wall will be visible (unless its fog colored). But if you make the fog strong then a smaller box is enough. But its not the box itself that causes slow vvis, its the actual map and elements that within it (for example if they are in an old aperture sphere). But it really depends on your map.
The compilation vvis slow, I'm sure that does not depend on the optimization of my map, because if I remove the big box that encloses the map, the compilation is fast.
I'll try to study me the optimization of the map, and then the use of texture tools. Because seeing the maps already created by the valve, they use tools such as trigger and hint. But I could not do it again in my map.
I had quite the same problem a few weeks ago and quaternary (thanks dude) linked me this thread that helped a lot to understand how to box a map without ruining the compile. Hope it'll help !
Thanks for the link , but I have another problem I can not solve. I do not generally opens the page ValveSoftwareDeveloper Wiki. He says the webpage is not available, but I know that it is, just that I do not know what to do.
That only means that you aren't understanding how VVIS works, and the optimisation of your map is step you missed. As mentioned above by Lp, read the article about Optimisation at Interlopers, it's incredibly good and should teach you the important things.
Listen, when you create a big box surrouding a given amount of brushes (your map), you are telling VVIS that EVERYTHING inside the big box must be rendered AT THE SAME TIME and you make it to calculate all possible positions the player could potentially be at (from inside that big box), and to "draw" all possible lines of sight from each of those positions to the rest of positions inside that big box... can you imagine how many calculations are those? THAT is the reason for it to take so much time in compiling its part. And also you'll get really bad performance, very low fps.
You MUST work on each of your map's leaks: into your hammer editor go to Menu > Map > Load Pointfile. This way you'll see a red line showing the leak. Close it. Bare in mind that brush entities (func_detail, func_door, func_brush, etc.) don't seal the map.
There is no better way to be a better mapper than that. PLEASE stop acting with laziness from the very beginning, otherwise you'll be a horrible mapper; this is the best advise I'd tell you.
, but I have another problem I can not solve. I do not generally opens the page ValveSoftwareDeveloper Wiki. He says the webpage is not available, but I know that it is, just that I do not know what to do.Is it possible that your antivirus is forbiding the site? 
useful tools and stuff here on TWP 
[spoiler]
[/spoiler]Thanks for the advice, and for having clarified the operation of vvis. Yesterday I started to read this guide on optimizing http://www.optimization.interlopers.net/ and now I will continue to read it. With regard to the webpage of valve software developer, I added chrome to the AVG exceptions; and I also disabled the windows firewall but nothing. : (
I'll also complimented on your map "Oxygen" really nice!