How to add class to the date Event Calendar

Hi

I’m using Event Calendar Version 3.1.4 | By Alex Tingle.
The date is displaying at the beginnig of the post like that :

[ 5 juillet 2013; ]

in the same class that content of post. I’d like to add a class, modify size etc. of it.
I’ve searched in files of extension but i didn’t find where to add it.

Thank you