First of all one has to demonstrate over time that they are a valued contributor to this site, that they have actual knowledge of what they are talking about, that they are mature in their dealings with others, and of course that they do not violate the site rules. They also need to have been members for a signficant amount of time.
If one has met all those requirements and wishes to take over an inactive coven, you can apply to the site administrator, Petrarca. Pet is the only one who chooses those who will be permitted to take over a coven. If approved he will let the person know. If you hear nothing back then you have not been chosen for the position.
Since it appears that you have only been on this site since January it is highly unlikely that you would be picked to head a coven.