For publications (like journal articles, conference papers, books and other published outputs), there are two "routes" to Open Access:
For other research outputs (like research data, exhibitions and theses), there is no "Gold" and "Green" - just Open Access! All that is required is the permission of whoever might claim copyright. OpenAIR is able to hold many different kinds of output, making them openly available online. As mentioned above, for more information about getting your research onto OpenAIR, see our guide here. We also have an entire guide on managing and sharing research data, available here.
Part of making your work open access will often involve making it available under an open license. There are various kinds of these, which enable other people to use and re-use your work in different ways. Some of the most well-known open licenses are Creative Commons - more details on these can be found here. The following are some examples of commonly-encountered open licenses: