I suggest you start at http://www.vatusa.net/join.php, which should progress you through the initial process. As to the sector files for VRC, you can find them on most ARTCC websites (the exception is Atlanta, which requires registration to access them). Once you have completed your Basic ATC exam and selected a facility to train at you should receive more information on how to continue training.
Where are you in the VATUSA - Join process? What was the last email from VATUSA that you have received? Realize that it can take approximately 24 hours to get the exam assigned, so if you were only verified today, it may not have assigned yet.