Hi Francesco,
There are no strict rules but I would recommend you to read the archive of this mailing list to have an idea about the way we proceed in this community.
To make a long story short though, we usually post request of help and people decide if they want to be involved or not. Sometimes, people find bugs and they share them on this mailing list. Some of them, send patches by email and I review them to see if they are worth to be included in the next release (and, luckily, they usually are ;) ). Sometimes, people share just ideas which is very useful too.
I hope this helps somehow!
JM