A screenshot clip is shown below. Create 7 blank layers in the main timeline. This is a pretty basic example, so you can leave them with the default names. Layer 7 should be the one at the top.
Re-size the symbol so that it fits well in the stage.
Align the symbol so that it is located it the absolute middle of the stage. After you have set the size and location of the symbol, you should highlight the single frame that it resides in. After you have two symbols directly on top of each other. You now need to apply the Alpha effect to the lower symbol. Find the panel and select it in the tree as shown below.