Elaboration to "Get In" requested...
The ways of visiting the country are increasing yearly. The easiest way to begin is to go on a tour. I like Young Pioneer Tours even though I was 69 years old at the time.
From the sound of the request for information you want a more extensive experience.
I got lucky on my first visit by talking with a member of the "Committee for Cultural Relations with Foreign Countries" and more than a year later was invited to teach English in a high school for 2 weeks.
The next visit I was invited to have a booth at the "Pyongyang Science and Technology Book Fair" and also brought a business man who met business people to search for business opportunities.
All my arrangements for the trips are now made by contacts in Pyongyang and the visa and airline tickets are picked up in the DPRK Embassy and the Koryo Airline office in Beijing, China, the day before going to the DPRK. I carry all the money I'll need with me in cash (I use RMB but Euros and US dollars are also good).