Ctrl-click the map at the position you want and select "New Place" and name the place.
Use "Metadata > Manage My Places" to create a new place of your own.
First search for a location in the vicinity of the place, where you want to drop your pin, eg., a city or a country. Select the result, press "+", move the pin to the location on the map you want and name the place.
After creating a custom place you can use it to assign the new place to a batch of your images by selecting the images and entering your new custom name in the search field in Places view, then press assign place. Or assign a place to one of the images, then drag all others to the pin, to assign the same place to all of them at once.
Also, after creating a custom place you can simply drag your images to the spot on the map where you defined your place. Your place name will appear, when you get close, and the images will be assigned to that place.
Message was edited by: leonieDF