In order to apply to take over an inactive coven you would first half to leave the coven you are currently in.
You would then send an e-mail to the Site Administrator, Petrarca, listing your qualifications for leading a coven. Things which are considered is the level of knowledge you have displayed in your activity on the site, your contributions to this site, your behavior towards others, your ability to teach and lead a group, etc. Send your application with this information and anything else that you think would be favorable to the application. If you have not heard back that you have been granted Priest status in the coven after 3-4 weeks then it would be presumed that your application has been denied.
Be sure you have your ducks in a row before applying as you only get one shot at it.