How did they make the curved top of the tent in the WWII Aid station?
I assume you aren't looking for complete instructions, but rather interested in main element used to construct tent. In such case Sports Arena Section / Skateboard Ramp (43085) has been used in Tan.
The models featured on Bricklink include a parts list, model file and instructions. You can see there that the curved tent is a skateboard ramp and the edges are 1x4 tiles attached with Technic pin 1/2.