Click your profile in the bottom left corner, and click on the Settings option:
Once you click on Settings, select Organizations on the left hand side of the screen
Click on Create New Organization Button
Enter your organization’s name, give it a handle (a unique username that other users can easily search for), and add an avatar to represent your organization. You can also invite teams or members to join your organization. Once complete, click on Share Projects button in the bottom right hand corner.
You now have the option to choose projects to share with the organization. You can set the permissions using the dropdown options on the right hand side. Once you've selected projects to share, click on the Share and Complete Setup to create the organization.