One valuable way of contributing to ORE is joining the Open Source Risk forum on this web site. Please sign up, join the discussions, provide your feedback and help us driving the project forward.
If you want to contribute as a developer, the starting point is to fork the ORE repository at github.com/OpenSourceRisk/Engine. The natural starting point and good way to become familiar with the framework is then working on test cases in one of the three libraries. As in QuantLib, if you want to contribute a larger non-trivial piece of work, then please discuss this in the forum first. Technically, changes should be contributed in the form of “pull requests” as described here.