If you are using Windows then there is a User Account program in the Control Panel to create new users. It is very easy.
But you realise if you leave her as an administrator she will be able to create a new userid herself to probably bypass your parental control.
She can do all sorts of other things as an administrator.
One option is to downgrade her from Administrator to "Limited User" (or whatever it is called in your version of Windows)
That way she cant create a new userid, nor download and install new programs.
To be honest anyone who is "good" with computers can probably bypass any parental controls you set up.
Surely it is better to explain to her some of the "problems" when using a computer, and also maybe get her to use the computer only in a family room and not in her bedroom.
Of course if she also has smartphone (or tablet) she can still get up to all sorts of things on that.