"The carpet's color goes well with the wall."
Translation:La couleur du tapis va bien avec le mur.
"Du" is the correct form of "de le". "De le" does not exist in french as you know it. "De tapis" alone would mean "of carpet(s)" Try to keep thinking that way : The color of the carpet -> La couleur du tapis. It's one of the few cases where a nearly word-by-word translation work :p