While looking at the property you wish to add civilians to in the Raid menu, click on the

button.
This will now show you the property on the "Raid Management" page:
Click on the property to expand its information:
Click on the Synthesize Civilians button to display the Synthesis menu:
Now select how many civilians you wish to synthesise and then click "Synthesize Civilians".
Each civilian will take 1 day to create. The first will be an Ether Reckoner, the second a Cydroid Technician and third a Raid Commander.
The Ether Reckoner will automatically dispense the Ether when the Cydroid gets back to your property.
The Cydroid Technician will automatically recharge the Cydroid after the Cydroid has finished dispensing.
The Raid Commander will automatically send the Cydroid to its next target.