Is it possible you can create your own forum
Well you'll need hosting of some kind, to purchase the software necessary. The funding. And knowing how to use that software, plus maintenance and people to monitor the site. As a non-educated person in this area I still feel certain those are some of the minimum things necessary.
But coming to a forum asking how to make competition may not be the best idea.
Now, assuming you've worded your question wrong, a thread is a collection of posts. Posts are the responses from other users. Threads go into whichever subforums it fits into. So you can make threads in Singles, Family, Teens, etc...
If how to make threads is your intended question, you've already done so by creating this thread.
Though your new threads won't show up immediately. They require approval first, by a mod. To my knowledge there is only one active mod and he logs in twice a day, on average. So it can be minutes or hours before approval, depending on how close your request is to the mod coming online.