Norwegian schools do not offer any extracurricular activities within the school beyond the scheduled physical education, where you do everything from soccer to skiing. Norway is country with close relationship to the nature and so Norwegians participate in a lot of social outdoor activities. There are many opportunities for those who are interested in participating in any kind of outdoor activity.
Most Norwegian teenagers participate in some kind of activity or sport with the most common sports for teenagers in Norway being soccer and skiing (both downhill and cross-country). There will many opportunities to join different local clubs for different activities within your new community. Your host family will gladly help you to find something that suits you.
There will also be opportunities for you who are music or art interested, when there are lots of organizations and clubs engaging in these areas. There are also big music events around Norway throughout the year.