How do I define the search path for personal library

[les_ander at yahoo.com]

Dear all,
i have a simple question.
Suppose I have my classes such as
myClass1.py
myClass2.py
etc
which I keep in a special folder ~/py_libs

Now
suppose I have a program that is not in py_libs
but I want to do
import myClass1 # note: myClass1 is not in the current directory

how can I set the search path for python so that it can
find myClass1?
thanks