This is one of those things that Pro makes soo much easier with families...
I threw together a small .capx that shows a sprite spawning random sprites in random times (even in random directions..).
It is simple events available to Free users.
https://drive.google.com/open?id=0Bx-ufu2WID53dHBSdEthaTBCckk (click the download arrow in the upper right corner of screen)