I have applied for a PR card and recieved a letter from CIC telling me that I can now apply for an "open work permit." I looked on the site and tried calling (busy) and got no help.
How does one apply for an open work permit?

Thanks!

You are likely referring to the open work permit granted following approval in principle of an inland sponsorship application. Such applications and the necessary supporting materials are submitted to the Mississauga case processing centre.