You have to move your people to the grass place. Click on the town where your team is and click the second option which looks like an arrow going away from a door
I would try and take on the electric one and the bug one before doing the fighting one. I tried it before too and it is too tough without doing that first
I dont know how to combine my guys to like evolve them, I have the 2 digimon i need but do they need to be a certain level? If you need to know, i have hawkmon and hyokomon and im trying to get buraimon