How to zoom in when I view my pictures on my Nikon d50?

When I review my pictures, I want to be able to zoom in and look closer at the pictures I have already taken.

Zooming into the displayed image is not the most user friendly feature of the D50.
Here is a link to the user manual as pdf file:
http://www.nikonusa.com/...D50_en.pdf
The answer is on page 55.

There's a semblance of that feature in the D50 but the magnification is useless. I say zooming in during preview is almost absent in the D50.