You can upload any scene you create in Unity as a region in Space.
Once your scene is assembled you have two housekeeping tasks;
When you create a new scene in Unity it will by default have a light and a camera. You need to delete the camera (by selecting it in the Hierarchy window and clicking delete).
You need to define where users arrive when they log in to your region; and what direction they are facing. To do this, once your scene is set up, from the top menu in Unity select Game Object / Create Other / Landmark.
If your Scene Heirarchy menu does not include Create other / Landmark, then;
Create empty object, then in the Inspector, add "Landmark behaviour" component.
This will place a new landmark item in your scene. In the Inspector window, set the type to Landing Zone and tick Spawn Point.
The in scene object is a yellow edged transparent plane which you can position anywhere in your scene. The yellow arrow points in the direction your visitors will face when they arrive.
Be careful to position the landing zone slightly above the terrain; if a tall avatar's feet arrive below the terrain they may fall through.
You can have more then one scene in your region.
1 - Create a new scene in your current Sine.Spaces project.
2 - Double click the new scene in your Assets to load it into the Hierachy. 2 - Design your scene. Be sure to save it.
3 - When ready to upload to the server click on 'Space' Scene Settings.
4 - Fill out the needed information, map pictures, and click Automatic Submission.