Why don't I "get" disney infinity 2.0???

I guess Ive been out of gaming so long I am a n00b now.

What exactly is the "toy box?" What are the different types of games modes? the wife ordered this thing cause it was on clearance and I am expected to show the kids (6 and 4) what all to do. Its got dick as far as instructions and youtube just seems to give me walk thrus instead of a fundamental understanding. At this point they have basically kicked daddy off the stick and are fighting each other (ironman vs thor) on some game type that looks to be a creative world.

Help me unlock its majic!

Plus I wanna play when they go to bed!