>Where should I start to learn about home improvement?

This question gets asked a lot here, and unfortunately, it's far too broad of a question to answer with anything useful, other than "Start by learning anywhere you can, be that books, TV shows, Youtube, or real people. Whichever modes of learning you prefer and have access to."

It's much easier for us to make recommendations of content-creators for specifics trades or skills you might be interested in, or for a specific project you want to tackle.

I can't point you in the direction of good wallpaper removal videos, but in terms of painting the walls once you're ready, This Old House has lots of great beginner-friendly painting videos on Youtube.