Changing the Scheme

My website is at http://www.coalcomic.com/

What I want to know is how to change the scheme or the default design or whatever it’s called.

I know I can go through Appearance > Easel Options and select “Disable default design” to get rid of what came with Easel but I don’t know how to edit the images or colors of the menu buttons (the part where it says Characters, Locations, ect.), the kind of lined grey part that appears behind the comic but in front of the background, and the pale grey text boxes that appear in the lined area (along with the bits in the sidebar that match).

I’m sorry I don’t really know the terms for anything.

https://ww.wp.xz.cn/plugins/comic-easel/