About how to change the Theme of the blog

Easy, first you need to go to this website:
https://hexo.io/themes/

Then you need to use git clone to clone the project:
git clone https://github.com/tufu9441/maupassant-hexo.git themes/maupassant

The last part is to change the configure of your website, change the theme into maupassant

Then you can use hexo g and hexo d to generate and deploy your changes.