Do and need a genesis framework for a theme

I keep reading about this Genesis framework, and am trying to learn more and do I need it. Here is my site https://www.nelsonmay.com/NelsonsNews/. I like the saturday theme, but I would like to change some colors and make the page wider. Is it OK to change some one else’s free theme? I would really like my site to look like my website https://www.nelsonmay.com made of word press. I really don’t have the time to learn coding, but I am hearing that a theme needs to be able to be updated with security patches over time.

Do I get a theme base on the genesis framework, or take the genesis frame work and try to build a theme.

I am new to this and it has me a bit confused.