Click on 'Edit course' in your main course page. Then select 'Contributors' from the top bar. You can add contributors by entering their Memrise username. Don't forget to click Save!
It is useful to share the workload of creating a course with another set of hands.
What can a course contributor do / not do?
A course contributor can: create levels, add items/words to levels/databases, correct errors, respond to course users, record audio voices, upload audio voices, upload images, delete audio files, delete images.
A course contributor can't: delete a course, delete a database, add a column into the database, rename a database or column, change testing styles and database options.