Well, everybody knows: the best way to learn programming is to program. Here are few freely accessible books on Python which should allow you to start.

1. Python Tutorial
2. Byte of Python by Swaroop C H 
3. Think Python. How to Think Like a Computer Scientist by Allen B. Downey
4. Dive Into Python by Mark Pilgrim
5. Learn Python The Hard Way by Zed. A. Shaw