Breivik's bomb

You can safely say that Breivik did not test detonate any bombs at his rented farm where he constructed the bomb, so the question remains where did Breivik learn how to build a bomb on that scale?

Was it just chance and a lucky first go which resulted in him blowing up the Government building?

Or was he taught how to construct the bomb by a bomb maker somewhere outside of Norway?

Dagbladet: Breivik's bomb