All documents for the MPGS can be downloaded here.
How to register as a doctoral at the Johannes Gutenberg-University Mainz is described in the Intranet.
The PhD representatives provide more information on their website.
The MPGS organizes a welcome seminar for all new PhD students twice a year. If you need more information between the seminars, have a look at the MPIP leaflet, ask your PhD representatives or the MPGS coordinator.