When you first run the app, you will see the main menu. From here, you have four options. The most important ones are of course the Play and Tutorial options. Tutorial gets you into the short in-game tutorial. Select Play and you get to create the look of your character. All the options here have no impact on the game and are purely cosmetic options.
Once you are done with creating your character, it will be saved and selecting your character will move you to the next step, creating or choosing a world. You will most likely have no world created yet so go ahead and create one. You don't choose any settings except for a name of the world. Go in to the world to start the game!