[git] Why is Github asking for username/password when following the instructions on screen and pushing a new repo?

Because you are using HTTPS way.HTTPS requires that you type your account access every time you try to push or pull,but there is one way too, called SSH, and it lets you to tell git, that I give you permission with my account for this pc, and never ask me again about any user access. To use it, you have to generate SSH key and add it into your Github's account just one time.To do that, you can follow these steps

How To Generate SSH key for Github