Hello
The building to build a hostile parlor is in the low right of the map, just above the statue and the house for the script.
The first option is use to build parlors and manage them, the second to see the hostile parlors in your territory and the last to search "victim" to build a parlor in their territory.
Once you defeat someone, select the first option, the defeated opponents will appear in the left, you can broxse them until you find the one in whose territory you want to build a parlor. You can then select the parlor you want to build.
One it's done, you can place girls to defend it, if you want.
Hoppe it helps^^