Are you allowed to work in Norway? Work Permits explained.
EU/EEA Nationals do not need permits to work in Norway but they do need to register themselves – more details are available here - http://www.udi.no/Norwegian-Directorate-of-Immigration/Central-topics/Work-and-residence/Work-and-residence-EUEEAEFTA-citizens/Temporary-registration-system-for-EEA-citizens/
For non-EU/EEA Nationals they are various options for work permits allowing employment in Norway:
Skilled Workers – they are different types of permits for skilled workers coming to Norway but you must have specialist training corresponding to upper secondary level, hold a certificate, have completed a university degree or have specialist qualifications. More details can be found here - http://www.udi.no/Norwegian-Directorate-of-Immigration/Central-topics/Work-and-residence/Apply-for-a-residence-permit/
Unskilled workers – two types of unkilled workers can get permits to work in Norway – Seasonal Workers - http://www.udi.no/Norwegian-Directorate-of-Immigration/Central-topics/Work-and-residence/Apply-for-a-residence-permit/Seasonal-worker/ and Seafarers on board foreign ships - http://www.udi.no/Norwegian-Directorate-of-Immigration/Central-topics/Work-and-residence/Apply-for-a-residence-permit/Seamen/
For more information on applying for a work permit for Norway visit the excellent Norwegian Directorate of Immigration website - http://www.udi.no/Norwegian-Directorate-of-Immigration/