Northern Myanmar is a region of Myanmar.
Kachin State has been de facto independent from central government's control since 1962, when the Kachin Independence Organization (KIO) unilaterally seceded from the Union of Myanmar. A peace deal struck in 1994 after a government army offensive made the arrangement more or less permanent, with the KIO-controlled area formalized as Kachin State Special Region #1, although KIO itself promptly split up into squabbling factions and the internal situation remains precarious at best.
In Special Region #1, Mandarin will get you a lot further than Burmese (or English).
Getting in depends on where you're going. For access to government-controlled areas like the capital Myitkyina, there are direct flights from Yangon, although the adventurous may also opt to travel by train from Mandalay (24-30 hours). For the rebel-controlled north, you'll either have to battle your way through massive bureaucracy to secure permits, or take the easier way out and enter via China.
Myitsone (Mali Zup), a confluence of Mali and Nmai Rivers, a naturally splendid for hangout and fun.