Circles in circles animation

hi there… anyone know of any tutorials or any codes on how to randomly animate circles moving around inside a bigger circles? the small circles will have a collision effect on each other and on rollover of each individual circle, the name of it will come out in the bottom… so the big circle will act as a wall preventing them from coming out…

yeah, by the way i have attched the file so more or less u will understand wat im saying.

really appreciate any feedback or help…

thanks…