In regard to the awareness part, they are asking participants to pledge to support the fast at http://www.savedarfur.org/pages/darfurfast>
I realize that, from a biblical standpoint, signing up on a public list to fast is a bit questionable (if not outright forbidden by our Lord). Yet doing so would certainly send a message of solidarity to the Sudanese people. Of course, clicking on the link is not necessary to fast, and your conscience can be your guide.
Either way, please consider sharing this with your congregations, so that perhaps we can wash our faces and fast together for a day for the people of Darfur.