Beginner lost in the sea of theme, knows what little he wants but doesn not know where to find it

Hi.

As you see below I don’t want much: configurable unfolding menu, single fixed background, transparent page backgrounds.
I understand the CSS vocabulary and principles, but could not write the likes of menus on my own. I wanna stress out that I’m a biologist, not someone unwilling to learn… But web development is beyond me, it’s too changing and full of conventions and makes my head hurt.
I tried tweaking a few themes but they’re all waaay above my head, just writing body { background-image: url(“background.jpg”} doesn’t work, and I ain’t guess how it could work, or if the theme would allow it…
I should be able to modify things but only if I know they are in the first place.

What’s the closest theme you know that would fit the bill ?
In hope I won’t get “RTFM” (which I did),
Thanks

Hi @Mehdi_Saada and welcome here,

after a quick look around, the Mainroad theme (Demo) could meet your requirements, give it a try and tell if something is missing or unclear

Here are two places where you can find more themes: