Adding hover images to lists

I’m currenlty trying to modify the RIN theme so that the left side links have an image directly to the right of the text of each link. I’m also trying to make that image change on hover. Unfortuantely while I’ve learned a lot about CSS today by researching this, I can’t come up with the answer. Do I do this in css or the sidebar template?

And does anyone know how to make the entire site go flush left?

Here’s RIN, which I used as my starting point.

https://www.brokenkode.com/manji2preview/