There are different ways you can support Geany users. Yes, even supporting users is a contribution to the Geany project.
Geany-users mailing list
You can subscribe to the Geany Users mailing list and answer questions, give hints to people who write there and so on.
You can also surf through the bugs reported at the Github issue tracker and see if you maybe can help users. Some issues reported are not actually bugs and maybe can be solved with your help.
Geany's twitter stream: https://twitter.com/GeanyIDE/