This the really the wrong place in the forums for this, needs to go in the classified's area. However, as long as you asked:
New leagues were stopped a while back due to an over abundance of openings in existing leagues. Leagues were taking to long to fill, so they stopped letting people form new leagues and even combined some leagues. Since then they have started letting new leagues be formed in certain cases. Not sure but I think you have to have a certain number of "new" owners, like yourself, wanting to form one. If you really want to form a new league, you will need to post your desire in the classified's section, gather enough other new owners to join you, and send a request (via support ticket) to WIS asking that one be formed. Assuming you don't want to do all this, you have two options, ask to be let into a private league by looking through the classified's section and sitemailing the poster, or wait for a public league to roll over. On the join league page you can see how many days are left for each league and whether they are private or public. Also, I guess a third option would be to just put an ad in the classified stating you would like to be invited into a league and wait...probably not real effective.
My recommendation would be to wait for a public league to roll over and play a few season there in order to learn the game. By then you will have enough experience to get into a private league. I know it frustrating and feels very exclusionary, but it is what it is.