The most important thing for a successful Open Source project is a vibrant community. This part of the webpage tries to connect Jinja users all over the world, to exchange their experiences and to help each other.
Jinja is one of the Pocoo libraries and uses the #pocoo channel on irc.freenode.net for both development specific questions and user support.
We also have a bot in the channel that logs the conversations. You can have a look at older discussions in the logs.
If you prefer discussions or support via e-mail you can use the pocoo-libs mailinglist.