Trouble understanding Normalized View Port Rect

I'm trying to set up a minimap of sorts with Normalized View Port Rect, and I'm having trouble understand how it works. No matter how I toy with the x,y,width,height of Normalized View Port Rect, it seems:

-the width and the height seem to have no effect on the height of the camera view port, really only changing the x and y do. -no matter how you set it up, the camera view will be against right against one of the 4 sides of the screen.

Could someone better explain how to set this up with dimensions I define for me? And if I use this method, am I going to absolutely have to have the minimap i'm making bumped up against one of the sides of the screen?

Normalized means every parameter is between 0 and 1, with 1 being the entire width/height of the screen. So (.25, .25, .5, .5) means it starts a quarter of the way in from the left and bottom, and is 1/2 the screen width and height. Since it's normalized and screen aspect ratios vary, that means you have to take this into account if you always want your minimap to be perfectly square, for example.