You can draw something brown, like GOO, and then alt+click it to copy the color, or search the internet for the hex values of brown and type it in the hex boxes. I don't see brown in the editor, but goo is 0x7F3F00
@IronRhino(View Post) @ForumTroll posted 4 shades of brown (the first two are the most brown). Type those numbers in the decoration editor where it shows the decimal values for red, green, and blue.
Also, I'm surprised people didn't know about that alt-click thing. You can also use it in the normal game to sample elements, and in the decoration editor, it will even sample the colors you see in heat mode or any fire/portal effects. I think clicking with the middle mouse button does the same thing as alt+click, but I don't have one of those on my laptop.