Captain America Superhero Squad

how do i unlock the characters in marvel superhero squad video game?

i have unlocked storm, dr. doom, abomination and Captain America.
how do i unlock everyone else

your can get a star on each level or you can find out more at

http://au.gamespot.com/?tag=nav-top;home&navclk=home

The Super Hero Squad Show Season 1 Episode 11 – Part 1/3 – O Captain, My Captain [HQ]