I know if you join the coven Spell Casters, you wil be automatically placed as a council so you will be eligible to post spells and articles. I also believe you can post the spell in the spell suggestions forum or other spells forum.
Oh, I didn't realize you did already lol. Ok, so the best you can do is to work your way to being promoted to Council by sharing your knowledge on your studies. I do not mean read a book/article or two. I mean to take your studies seriously, practice what you study to gain personal experience the. Share it amongst your coven and maybe the leaders in your coven will see how much you know what you are talking about and decide to make you council
From what I learned, you can join another coven but you will have to create another account since you can only be apart of one coven for one account. I would first look at any threads in posting spells in your coven to see if your coven has a way for members to share their spells/articles. If you cannot find a thread then ask one of the leaders in your coven to see if you do have a system for members that are not in a leader position share spells and articles.