Below are some resources where you can find help in using Graphite.
Font development - join the Graphite Font mailing list to connect with others who are developing Graphite fonts.
Graphite system development - join the Graphite Development mailing list to discuss Graphite system development.
Graphite application integration - the Graphite Development is an appropriate mailing list for these discussions.
Bug reports - can be sent to https://github.com/silnrsi/graphite/issues
GDL Tutorial - font developers who would like to learn GDL may find the tutorial helpful.