You can make your Community private or public in the following steps:
1. Click on the Commerce tab on the left side bar.
2. Click on Community.
3. Enter the Community Name
4. Select the Public or Private radio button
5. For an already created community, click on the community.
6. Click on the Settings button.
7. Scroll to the bottom and select the option you want (public or private).
7. Watch the video below for more information