In the beginning, your community will probably look a little like this:
The founder will be starting most of the posts, initiating discussions and keeping the activity going. At this stage the founder needs to be persistent. S/he needs to start a discussion then individually message members to reply. They need some prodding before it becomes a habit.
Gradually, other members will start initiating the discussions. Your work load will slowly shift from initiating discussions to ensuring these discussions get a response.
Key lesson? Stick with it. Stay persistent. Start a discussion and personally message others to reply to it. Don’t give up. Communities take time to get started.