you mean you have your files for the GitHub Page and you want to transfer that on a GitHub repo ? even a drag-and-drop will do,

No I mean I need to enable file upload to my website, I don’t need drag-and-drop for a GitHub repo, I do that with GitHub Desktop.

you want to use FTP to transfer files ?

where is the server ? is it a GitHub repo that was turned as GitHub Pages ?

if you have a separate server, then I think you have the complete details of the instruction on how to move files at that server,

in the past, if I can still remember it correctly, I tried Microsoft IIS, once you setup the server locally, you still need authentication and authorization for the FTP service, so you can move files on the server and you need additional setup if you want to make that available over the Internet, not just on the LAN

oh. thank you for the clarification @yoannchaudet . Just one more thing, Can I add a FTP to my website to upload file to my system? like, a visitor of my webpage clicks a link which enable him to select files and upload them to my local machhine?

Well, yes, but it doesn’t have anything to do with GitHub Pages. You will need to build an upload form, run some server software on your local machine that can handle file uploads, use a DynDNS service to give your computer a domain name that automatically updates the DNS record with your IP address, and potentially leave your computer running 24/7 to make uploads work all the time.