There isn't a way to change the colour of the background in the wireframe view. It's a 3D view and it kind of makes sense that, as there is no bounding region, that the emptiness is black.

When you're creating plots, and working in plot view, it is rendered as if on a page. You shouldn't work in plot view though, as you can quite easily make changes/adjustments that you aren't what you're intending.