How can I redirect from my root index folder into a subfolder on Github Pages?

I successfully published a web project on github pages. However, I have a problem. I can't access the html files in a subfolder from my root folder.

This is my root folder: Screenshot of my root folder

And I want to redirect some links to one of these files in the folder "detailsites": Screenshot of my subfolder

Everytime i click on a link which redirects me on a html file in the subfolder, I get a 404 error. Have someone any ideas why this is happening?

The links to the files in the subfolder are looking like this: https://[username].github.io/[repository]/detailsites/interview.html

Thanky you.