If using a 10.6 DVD:
Boot to the Installer/Utilities DVD, but do not install.
Answer only the "what Language" question and wait for the MenuBar to be drawn.
Choose Disk Utility off a Menu and erase or partition the Hard drive.
GUID partition Map and Mac OS X extended, journaled, should be the defaults.
If I am understanding you correctly, you replaced your old HDD with the new one inside the Macbook.
Before you installed the new HDD into your Macbook, did you format it? If you did not, it will not work.