Hi...
There has always been pure souls in Stencyl to help other Stencylers. I'm definitely not one though

But would like to share my idea.
1. Create 3 graphics. One with 1 star highlighted, another one with 2 stars and another one with 3 stars highlighted.
2. Create an actor named 'Stars'. Create 3 animations with names like 1Star, 2Stars & 3Stars. Place the graphics you created in the respective animations.
3. Hope you have already created an attribute to track bullet count. If not, create a number attribute (I would name it bulletCount).
3. When the bullet is created, 'bulletCount' is incremented by 1. Inside the bullet actor's even, you can use 'when created' event and write the following code:
increment bulletcount by 1 (there's a green block which can be searched as 'increment'. Use that block)
4. When the game is over, create an event
if bulletCount = 1
create actor 'Stars'.
otherwise if bulletCount = 2
create actor 'Stars'.
switch animation [2Stars] for last created actor (Search for switch block and you'll find this blue block)
otherwise if bulletCount = 3
create actor 'Stars'.
switch animation [1Star] for last created actor
Now you can also create the actor 'Stars' above all the if function if you know what I mean. Also, set the default animation to 3 stars.