I found this excellent article from Thomas Jakobsen: http://www.gotoandplay.it/_articles/2005/08/advCharPhysics.php where a very neat and simple engine is implemented (thanks Mr. Jakobsen).
It is very well explained so adapting it to my little lab was not very hard.
Here I proudly present my very first simulation!
I am perfectly conscious that it lacks of a lot of things...namely collision detection, a proper stable, precise integrator, an optimized implementation...and a long etcetera...but it's just a baby!
Here is a zip file with the code (an extension from what I presented in the last post):