The interview is a general get to know you and your background. If they confirm youve passed that stage, you'll be brought onto the floor to try an sell an item to a customer, so ensure you know details about a certain product in order to sell it to a customer sucsessfully. If you pass that stage, they will bring you to the back again, where you will take a written exam based on siuations that may occur in the store on a day to day bases, and asked how you would deal with the situation if ever presented with it. You are then brought to a section of the store and handed a sheet with questions based on the isle your in. If you answer them to their satisfaction, including passing the rest of the interview, you should hear back within a couple of days that they think youre fitting for their desired role!
Be polite and focused