http://www.modchip.com/pictures.htm
The above link is to just one place i went to few days ago. I got my chips over a year ago. But i just installed one into the "newer" small PS1. And the above site was were i found the install pic i so much needed.
You can order a chip(about $10) online from a few places. But you will have to instal/soder 6 different wires to the motherboard of the PS1 yourself. Once you do, it will play back-ups, and even import games.
I have installed a good dozen myself. 4 being the new small PS1's(and harder/cause size). But be carefull if you never sodered before. You don't wanna mess up.
If your PS1 came in a more Black box(model after August 2002). That is the 2nd small PS1 model. So you should have a look at the pic. and see what your going to have to do.