Once you have created your account on GitHub, you will be able to create a new repository from the GitHub web interface.

Once you have created this repository, you will see (detailed in GitHub on your repository page) the URI for it. You can then set this as a remote from your local machine and then push to it.

The procedure on your local machine would be as follows:

git init
git add . 
git commit -m "initial commit"
git remote add origin https://github.com/[your account]/[your repository]
git push origin master 

I think perhaps part of your confusion is not recognizing the difference between Git as a version control system and GitHub which is a service for hosting projects. Git will work completely independently of GitHub. Or you can use GitHub to host your core repository as described above.

New fork because the old project is abandoned;
The URLs are now (htmlpreview -> html-preview):

• https://html-preview.github.io/
• https://html-preview.github.io/?url=https://github.com/bartaz/impress.js/blob/master/index.html

previously:

The most comfortable way to preview HTML files on GitHub is to go to https://htmlpreview.github.io/ or just prepend it to the original URL, i.e.: https://htmlpreview.github.io/?https://github.com/bartaz/impress.js/blob/master/index.html

Are you sure (and how are you sure) that there is something pushed in this repository? This window usually appears right after a repository is created without anything in it.