From StarWars.com:
"We contact you in the gravest of circumstances -- the space station known as Juma-9 has suddenly lost contact, and the two Jedi who were there seem to have gone silent. We are certain the Separatists are behind this cowardly attack. Only they would attempt to destroy a defenseless communications outpost. Something must be done - and that is where you are needed.

We need recruits to head to JoinTheCloneWars.com to learn how they may help us fight. In the coming weeks we will be offering training, news, and more to discover who amongst you has what it takes to fight along the great heroes of the Republic.

Wait...we are getting word from Juma-9! It is General Kenobi! Head immediately to the command center to receive his transmission!"

See also:
Star Wars The Clone Wars: Republic Heroes Coming This September