u/Dry-Highlight-7038

Hello! I recently thrifted a Lundby “Frog House” (Göthenborg) and I am trying to understand what kind of curtain rod fits into the holes at the top of the window frame-and how the whole thing operates. The house is pretty banged up, but the windows seem in tact. I will try to create curtain rods and curtains myself, and not purchase them. I have watched tutorials and looked at photos and haven’t been able to understand how it functions. Thank you for any tips!

Also-is there a way to test the electric system before I try to install lamps? An inexpensive transformer to use? (I am in the US.)