how can we create a login system that can actually login to actual website that is not owned by us. We want to get username and password from the user and try to login to the website like github. and be able to show all the information like their post and their projects.
That would depend entirely on the API of the website. Are the details available to you? For example, do you have a URL for the webserver’s login endpoint? Do you know what algorithm the login webpage uses to encrypt the user’s password before it’s transmitted to the webserver?