If you are designer, programmer, or if you simply wish to propose an idea, you are welcome in our chat room or on our mailing list, or even our forum or bugtracker - drop over to the Contact Us page and pick your favourite.
To contribute as a programmer to the Gluon project, you should be familiar with how Git works. A guide to working with git can be found on KDE's TechBase. Since Gluon is a KDE project, to be able to push to the main Gluon git repository you must have a valid KDE account. Get this by following the instructions on http://techbase.kde.org/Contribute/Get_a_SVN_Account (even though it says SVN account, this is a general way to get an account for the KDE services). See also http://identity.kde.org/