Notice the layer palette has a mask on it.
This lets you know this layer is a mask :)

If your image looks like this with the outside filled,
click on Masks/Invert.

Then Masks/Delete
You must do this.

Add a shadow.

To define it, I added another shadow.

These are the effects if you use another shadow color.

light purple

I opened a large transparent image 500x500.
this gives you room to add your name.