I used an Ateco 825 which has a large base. THAT is what you are going to want. The bigger the better. That will determine the size of our cupcake center giving you lots of room for fillings. Place the back of the tip onto your cupcake and twist it down until you think you are at the middle. Twist back up and you should end up with the center of the cupcake pulling right out. Use a spoon to fill your cupcake with whatever filing you desire. Place the top back on and gently press down. For a full step by step tutorial with images visit this post.