The system here that allows members to start covens has been disabled. Meaning, new covens can't be started here.
But if you mean in real life off the computer I think one could post a newspaper article or get a website up for people in the near community could see and possibly you may go from there.
It's like starting a club, get up some funds and some members more likely to be close friends who will stick it out and help you begin the coven.
Figure out what you want the coven to b based on an find out if anyone of that origin/belief/practice/goal etc... lives near you and maybe go visit them and talk about it.
Or go to any various community businesses known for helping to start up clubs and things. And once the coven lifts off and you start getting members you won't need that business anymore.
As such you said you mentioned that you don't believe you are experienced enough so if you're looking for a coven in real life just go look for one. Or talk someone that is highly experienced into becoming your coven leader and start one together.
You don't need to be a masterful Priestess of Priest to begin a coven, you really just need to know how to spot good experienced and knowledgable members to make them council or something of higher power and it also helps to be good with people.
Hope this helps