Easy! Read the description under the dungeon you're going into! For instance...
Little Wilderness has 5 tiles which means you have to move 5 times in order to get to the next floor. So every floor has 5 tiles. (And you may roll the poke dice whenever you feel like it, but you must roll it once each floor
) Anyway, roll the floor die and it will show you how many tiles you move :3 Little Wilderness has 3 floors, sooo good luck! ^^
Also, say you're on the 3rd tile out of 5 and you get a 3... you'll go up 1 floor and be on the 2nd tile