Changing the color of your content area?

Can also tell me how do I accomplish this “Changing the color on the content area”
by default the content area comes with a slightly gray background how can I change that to a dark or darker tone.. What files do I need to edit that code into?

Thanks

Most if not all color attributes of a roku channel application are set through the theme attribute for the app using roAppManager.
http://sdkdocs.roku.com/display/RokuSDKv48/roAppManager

At other times it might be preferred to alter the image you are loading yourself - like for the description bubble of a gridscreen - that has to be edited on the actual image for the bubble as transparency is broken on gridscreens.