You can get help with CsoundQt on the main Csound Mailing List, but for CsoundQt specific issues, you can join the CsoundQt Users Mailing List, for ideas, bug reports and suggestions. This mailing list is also available as a Forum on Nabble.
The CsoundQt Wiki offers a number of helpful articles. It is also open for contributions by users - create a new article and share your knowledge!
The Documentation pages are still not complete, but hopefully CsoundQt is intuitive enough that it should be enough to get you started. There is also some information on the Help menu in the CsoundQt application.
Errors can be filed and wishes for enhancements desciribed at issues tracker.
Alex Hofmann has created a series of video tutorials for CsoundQt:
Other video tutorials: