Upon starting a new file in Super Mario 64, you will emerge from a pipe outside of Peach’s castle. There’s a lot of room to experiment with the controls out here, so it’s best to try and get used to them before entering the castle. As you approach the front door to the castle, you will be stopped by Lakitu, who will act as your camera in the game. Enter the castle and you will be in the foyer, which is the first hub for levels in the game. There are a bunch of doors here, but all of them except for one will be locked. You will need to have collected a certain number of Power Stars before you’re allowed in the locked doors, with the number on the door indicating the amount of Stars you need.
There is a total of four main levels in the foyer, but only one is available from the very beginning, which is to the left when you enter. There’s also a few other doors, but these are locked and require you to get a few stars under your belt first. The door with the big star on it, up the stairs and to the left, requires you to obtain eight stars before it can be opened, leading to a boss level. The big door with an actual lock on it requires a key, which you acquire from a later boss. The two wooden doors on the base floor lead to a hallway, with another door with an actual lock, as well as a door leading to an outdoor garden area and a fountain. Since there is only one level available at the beginning, go into the door with no number on it to find a large painting. Jump into the painting to enter the level.