The Duolingo team tries to focus its efforts on building free language courses to help as many learners as possible around the world. Courses are constructed with help from the community of volunteers who contribute to the Incubator. You can cheer for your favorite teams and follow their progress as they get closer to finishing. You can also sign up to be notified when your desired course is available by selecting it from the course page.
If you are bilingual and want to help teach others, you may also apply to contribute to a new course. Proposed language courses are considered when there are enough great candidates to build them and learners and testers to help improve them.
We have a long list of courses we intend to release, and we also monitor the forums and applications for new potential language directions. If you want to suggest a course, we encourage you to visit the forums, search for suggestions that have been made in the past, and add your vote or comment to existing posts. That will make the request more popular and make it stand out more, encouraging more people to add their votes.