No vacant positions at present time.
In order to teach at a Danish gymnasium you must have an accredited education (see: www.fivu.dk). This is typically a Master of Arts level education in your chosen subject, enabling you to teach at an upper secondary level.
You must speak fluent Danish, and you must have passed the 'Studieprøve'. (Read more about this in English at: http://eng.uvm.dk/Fact-Sheets/Adult-education-and-continuing-training)