running python c.py will do what you want.
if __name__ == '__main__':
from a import dummy1
from b import dummy2
usualy you need to be sure that import didn't fail and use exception but probably this will be later when you will feel confortable enought with python.
Edit: two things:
- change url to point to your python version instead of 2.6.6
- i assume you don't ask about something like call, eval, exec( see the docs for details)