Blend tool would be one way, though you'd need several blends.
Effect>Distort and Transform>Transform (and specifiy number of copies) would be another.
(By the way, holding the Ctrl. key while making the star makes it a proper American star).
Object>Transform>Move one direction at a time you first do one as a copy then hit command d to duplicate say horizontally first then you select all the horizontally do the same but vertically this time and make it a copy then hit command d the number of time you need
Effect>Distort and Transform>Transform select the number of copies you need in one direct minus one of course then do the same in the other direct.
The Blend method is good as you can specify the distance and number of items
then there is a funkier way but one with good control specify the area as well as the number of repeats and space between and scale it to fit.
Make a rectangle the size of the area you want the repeat to cover.
Turn the star into a symbol
Select the Rectangle and go to Object>Path>Split into grid specify numbers of rows, columns and gutters
then while still selected go to Effect>3D Effect>Extrude and Bevel
Give all the rotation setting a setting of "0", a bevel of none and extrude height of 1.
then go to map art and turn on invisible geometry.
The select the star symbol and scale to fit if necessary. If you do it correctly by actually making the star latter and measuring the grid elements or adjusting the symbol you will not have to scale in the effect.
You should see all the grid elements populate with the star.
This way will also allow you to populate some with one symbol and others with other symbols
You can then turn the effect on and off and have different set with different stars or other symbols.
Turn on scale strokes and effects and go wild!
With the other quesion answered:
P.s - Does anyone also know if I can change my existing user name while still keeping the same account or will I need to just make a new account?
I told you that you would need it, Illustratornewb. And the answer is here (no need to start over):