Funnily enough the main language spoken in Norway is Norwegian (norsk) which is divided into two written forms; bokmål (85-90% of the population) and nynorsk (the remaining 10%, mainly in the west and north of the country). A quick Google search will find you resources to learn Norwegian, which is grammatically similar to English and Swedish. The rate of English-speaking in Norway is very (relatively) high due to its use in education and Norway's high exposure to English through trade and tourism with the United Kingdom. According to the latest figures, 91% of Norwegians of working age have "some knowledge" of English.

Todays Norwegian children are learning English already from the year they begin at school (1st grade). So most teenagers, young people, and grown-ups up to 50-55 (maybe 60) should be pretty fluent in English or able to understand a lot of it.