why I can't apply colors on the wall

khung90s

there's something suspicious about this:https://www.renderosity.com/mod/bcs/?ViewProduct=125812. I tried moving wall options to materials but it won't work, this is stupid. 

kaotkbliss

I don't have that product so I can't test, but I'm guessing you probably need to move down to the surfaces tab (right under the parameters tab you have selected in the lower right on the 2nd picture) then select your wall in there, then apply the color.