Problem to start playing in a simple map

[thunderstorm]

Whenever I start the map it gets totally dark
I even inserting a light box and as a floor.

And these MESSAGES:

LIGHT NEED TO BE Rebuilt
PATHS NEED TO BE Rebuilt

What are these errors, how can I fix them?

[shellc0de]

You have to rebuild the lightmaps or probably more accurately, build them for the first time, to do this click the little green cube with the light icon on it which will 'rebuild all' meaning paths, lighting, geometry and other stuff.

[Blade[UG]]

You can't have learned how to make a map without also learning how to build the map ..

[thunderstorm]

Ok I will try to build using the button. Actually I believe that I make the map correctly.
..So I spot be making something diferent of the normal.
Thanks for the hint.