First go to "Settings -> Accommodation types -> Add New"
Create an accommodation type called “12-bed dorm (female)” or similar.
Make sure to indicate that the object type is “bed” and that number of guests is set to one (1).
Then enter the price per bed and person.
Once the accommodation type has been registered, add an accommodation unit for each bed in the dorm.
Name them Bed 01, Bed 02 etc but also good to add the room name to the bed, so you know what room the bed is in. Also because each "bed" needs a unique name. Otherwise the system think "Bed 01" in 12-bed female dorm is the same bed as "Bed 01" in 12-bed male dorm.