Short answers, pulled from the story.
Vidkun Quisling established the Nasjonal Samling party on the 13th of May 1933. The group failed to win a single seat in the Storting during the 1933 parliamentary elections and received only 27,850 votes representing just 2.2% of the total ballot.
Strong belief in Romantic nationalism and authoritarianism dominated the NS ideology from its inception. The party asserted that its symbol, a golden sun cross on a red background, had been painted on the shield of St. Olaf and used colors matching the coat of arms of Norway.
Germany invaded Norway on the 9th of April 1940 and later that same day Quisling marched into the Norwegian Broadcasting Corporation studios in Oslo. He made a radio broadcast proclaiming himself Prime Minister but his attempt to seize power failed within hours of the initial broadcast due to King Haakon VII refusing to appoint him.
The party served as the sole legal political entity of Norway from 1942 to 1945. Nasjonal Samling membership rose to 22,000 in December 1940 and peaked with around 44,000 members in November 1943 before the end of the war.
The party was made illegal and disbanded on the 8th of May 1945. Nearly 50,000 individuals were brought to trial following the liberation of Norway in May 1945 and authorities executed Vidkun Quisling for treason along with a few other high-profile NS members.