Can't seem to start on this

[Kene Meniru]

This sounds so simple but being new to python I am finding it hard to get 
started. I want to create a module which I will call "B". There will be 
other modules called "C", "D", etc, which will most likely be imported in 
"B". Then I want the user to import "B" ONLY into another file I will call 
"A" in which commands such as the following will be entered:

snap_size = 10
LinearMark(name)
LinearMark.put(name, length, rotation, (x,y,z))

The file "A" allows the user to enter commands that provide global variables 
as well as to use classes provided in modules "C", "D", etc, in the manner 
shown in the sample above. For example snap_size is a global setting. 
LinearMark(name) creates a linear mark of the provided name. 
LinearMark.put(...) places the LinearMark object using the provided 
parameters, etc.

How can I make this possible? I am guessing I have to instantiate the 
classes in file "B" but typing LinearMark(name) in file "A" generates an 
error. Eventually I will provide a gui but I want to separate usage so there 
is no dependence on the gui to run this application.

Please help.