Want to create some cool effects in illustrator? Create a new layer. Draw the ellipse tool and add radial gradient, then go to transparency and select screen. Then create the star tool and deselect stroke. Drag and place the star shape on ellipse and group them. Then duplicate that layer to make multiple sparkles on different layers. Resize other sparkles by holding down shift key. One can change colors of other sparkles. This will help you in making a good background.