You are missing a feature? Just create a new Issue for this project. Please use an agile form when writing a new story like "As 'ROLE' I require 'FEATURE/FUNCTION' to have 'DESIRED_BENEFIT'." Or in case you want to file a bug, it would be good if you provide as much information that is required to reproduce the bug.
If you are interested in suggested issues from other users too, tag it with a smily (githubs 'like it' button). Those ones with the highest count have better chances for being scheduled for the next release cycle.
Seek contact, let me know if you plan to work on something to avoid double work. For setting up your local environment please follow the DEVELOPERS_MANUAL.md
Fork the project for being able to create pull requests.
Please work along the issue log and create feature-branches and use pull requests. Don't start huge refactorings especially on architectural design (those are only accepted if we agree upon them, i.e. you need to communicate as in real life ;-) )
It might be that I need to add you to the collaborator role on this project the first time you want to push your feature branch. If that's the case let me know.
Look especially for features marked with "HELP WANTED"
Any support in terms of infrastructure, software licences or donations are welcome. I plan to integrate a sponsor credit screen or something like this, when a critical user base will be reached.