A box that's fullbright and 90% the same exact gray texture..

It's not hard to place lights. You just point and click. You should try and put some more work into a layout that's not a box, give it some detail and textures, some variation, some lighting...

Maybe. But this is my second map.

Maybe use a different texture here and there

It's not pretty but it is real fun. You should do it up into a paintball arena or somthing because the map is all grey.