Welcome to SimGrid!
If you don't know were to look to start with, you should probably have a look at the following presentation first to get the basic concepts. Afterward, you probably want to proceed to the MSG. Of course, if you're curious or if you know what you want, you may prefer to go to SMPI, or even GRAS.
The scientific bases of the SimGrid project are presented in a 3 ou 4 hours-long tutorial. It can be found at the following locations.
- https://gforge.inria.fr/plugins/scmgit/cgi-bin/gitweb.cgi?p=simgrid/propaganda.git;a=blob_plain;f=tutorial/simgrid-tutorial.pdf;hb=HEAD
- http://webloria.loria.fr/~quinson/blog/2010/0628/Tutorial_at_HPCS/
