Here's how to make a Sagan from scratch.
Open the Sagan Palette in your Map View (this top-down view of your Sagans):
Click and drag the Sagan onto the Map:
Another way is to open the Sagan Palette in Map View and double-click the Sagan you would like to add to your Map. Doing so will automatically place the Sagan and open it.
For more on how to Build in Sagans, check out the How to Build a Sagan Training Video: