Top menu >> Customers >> View customer >> Locations tab >> + Add a location

To create a location manually you have to go to the Location tab on the customer page. 

View the customer you would like to create a location for. 

Click on the Location tab and +Add a location after

Enter the Location name and any other information. It proves to be helpful to incorporate either the city or a partial address to the location name, this will make it easy for users to identify the location when they are looking for it in a dropdown field anywhere else in the application. 

Click OK when done.