Changing header background image using Emilia Theme

[reignbeox]

Hey man, I am currently doing my first steps in website coding and I looked at your templates just to understand stuff and pick it apart.
For the life of me, I can not find any way to replace the header background image. Those random symbols.
I also can not find the light mode dark mode feature. Also, no idea where the color is.

Also on the Jodie theme, where can I replace the lion head icon?

Both issues are completely beyond me. I am sure that I read everything in your readme files but I just can't find an answer to something as arbitrary as changing those elements.

For the record, I just cloned the repo and installed nothing. Hosted the websites directly via render.com and am editing the code with vs code.
Is it me?