This is a quick summary to build Github Pages with Jekyll Theme on Windows
https://rubyinstaller.org/downloads
C:\>ruby -v
You can install Jekyll using gem since Ruby is installed
On Ruby Command Prompt,
$ gem install jekyll bundler
$ jekyll -v
There are many ways to add a Jekyll theme to your repository. In my case, I downloaded Jekyll theme(Clean-Blog) and copied it to my repository.
$ jekyll new [GithubUsername].github.io
Enter the directory you have just made.
$ cd [GithubUsername]
There are few more steps left, but publish the blog locally to see if it works well.
$ bundle exec jekyll serve
The site should be up and running on local host:
baseurl: url: "https://hskim2019.github.io"