If you are coming from central Paris the simplest way to get to Paris 8 University is to take the metro line 13. The last station on the line 13 is Saint-Denis Université, and the entrance to the University is right in front of the metro exit. (Watch out, the line 13 which heads north has 2 directions, make sure to take the train towards Saint-Denis).
You can also calculate what itinerary on the following site http://www.ratp.fr/ and simply enter St-Denis-Université (METRO), Saint-Denis as your final destination.
The workshop will be heald in conference room B 106. Once you enter through the main entrance the first building on your right will be building B1. On the first floor you will find the room B 106 on your right hand side.