Luxrender, help me

Hi, I am new to LuxRender, for several days I’m trying to get the rendering of a wall, as seen in the screenshots, but I can not.


1 How I can decrease or increase the power of sunlight guy?
2nd textures Why not rendered correctly?

Excuse me if my english is bad, I’m actually using the Google translator to write this.
I also want to greet everyone in the forum.