A1: What world are you talking about

A2: On your map find were the arrow is going then open that door an you wii find leon

A3: What do you mean first part?
Do mean Sora's story or the tortoral or first world?

A4: The first part of the game is the tortoral.. here they show you how to use the control and how to use the cards that you use in battles... After the Tortoral they are going to show you how to use the controls outside of battles.. fight the Heartless you see in the Room and hit all the stuff you see the looks like a target on it and you will get other stuff.. walk up to the doors and it is going to tell you how to use the Map Cards to go to room to room... to know where you are at and where you are going press select to open the map... once you are done of the first world you are going to get cards to move on to other worlds.. good luck

A5: After you beat the tutorial by doing what the hooded man tells you, look on your mini-map (upper-right hand corner [if there isn't one press start to go to the menu and pick config. Then go down to mini-map and choose show mini-map] of the screen) look for a red arrow and go to that closed door. Open it to continue. You'll meet Leon.