Irrlicht Engine

I don't know much about shaders
Is it possible to download somewhere cubemap shader and use it like in shaders example to get cubemap reflections?

And second question. How can i make postprocessing of each frame to make it, for example, more or less bright or contrast?

Cubemaps are a new feature of IrrSpintz so you should take it from there. Postprocessing had been implemented a while ago, use the search function to find it.

What is IrrSpintz?

yeah u should be ashamed for not searchig the forum...

Just search the Forum, its the Irrlicht Engine with several improvements made by Spintz.