When you get control of your character, run to save (you don't want to repeat cutscenes). Now go back up and talk to the people. Soon another cutscene will begin (you can skip some cutscenes by pressing ). You will find yourself in a cave. Save when you find the save point.
This boss is pretty easy; just circle him until he stitches then attack him.
Another way to do this is to stay behind him and keep attacking from behind, because he can't reach your character there.
Keep going and grab the chests, then go through the part until you get to a boss and four chests. Don't die; kill it. You should be at least level five. After it's dead, go back and find papa.
Before you go searching for him, shop for armor and wait around until three. You'll see him going somewhere. Follow after him and chase him into the place.
Go through and keep going through until you reach a blue switch and a red switch.