To add a spawn position, you just need a game object with a Network Start Position component:
- Navigate to GameObject | Create Empty, rename it Spawn1, and set its Position to (0, 1.4, 1)
- Navigate to Add Component | Network | Network Start Position
- Duplicate the object (Ctrl-D), rename it Spawn2, and set its Position to (0, 1.4, -1)
- In Hierarchy, select NetworkController. In Inspector, Network Manager | Spawn Info | Player Spawn Method, select Round Robin
We now have two different spawn locations. The Network Manager will choose one or the other when a new player joins the game.