Howdy Emanuel!
We’d be happy to help. First off, though, I just want to check that you do indeed have an active license for one of our products (e.g. PRO). We use the Pre-Sales forum here to help answer questions about our premium plugin features and take technical support questions in our premium forums, which are open to those with a license.
If you have a license, great! I’ll move this thread to the PRO forum and we can go from there. If not, will you please post to our WordPress.org support forum? We hit that forum once a week and would be happy to meet you over there.
In the meantime, please do check out our Themer’s Guide which includes a great deal of information on how to customize the calendar styles.
Cheers!
Geoff