You must hold a residence and work permit in order to reside and work in Denmark, if you are a citizen of a country outside the Nordic countries or the EU/EEA. Whether you can obtain a residence and work permit depends, first and foremost, on your qualifications.
The rules also apply in the case of voluntary/unpaid work.
A number of schemes have been designed in order to make it possible for highly qualified professionals to get a residence and work permit in Denmark.
Please visit Denmark Immigration Service website for Work Permit information’