Changing page and side colors

Just have begun with wordpress, but begins to get a bit knowledgenow

But I have some questions:

How to change the color on the page inside the orange frame in the midle. That page is edited in CKeditor, but there is no button for background color just for that page there. Tried the style.css to edit, the colors around has been changed, but not the color inside the orange frame

How to change insert widgets in or get rid of the black area on the right side, also with an orange frame around it?

The page: http://hmhk.no

https://goo.gl/photos/jhQ2qroPkX6gTcKu8