However, when I try to complete the "newbie" challenges on Frontendmentor, I have no idea what to do.

OP I started in August 2021, was lost, learning things again and again, courses, tutorials, learning every single programming languages, depression, feeling like coding is not for me.

Someday things will make sense! Someday you will be fluent making in Intermediate CSS challenges from frontendmentor! Hold on, this is alright :)

I completed theOdinProject as a last try yesterday and, now my basics are clear! So it takes time, you will feel lost and sometimes learning burnout. I know JavaScript but needed something like odin project and now I'm happy to achieve my dream :).

Also, don't worry that you can't complete the challenges now! You will learn more and feel like "yeah, I was anxious over nothing".

Cheers.