Studies and work (Oslo)

Hello guys,

I wanted to know if someone knows the rule about working and studying in norway at the same time.
Here is my situation : I am working full time and would like to take a study on the side. Some courses require my attendance and I will have to skip work 3 days in the semester.

What are the rules regarding this?
Do I have to take that time from my holidays? I think the company should allow me to leave work without taking it off from my holidays. Or maybe like only take 1 day for the three or something.
re there any written rules about this I could find on the internet?