I have a white Macbook 2009 on OSX Lion. It came with the OSX Snow Leopard CD, I erased the HDD and am trying to install the OSX from disc but am getting "cannot install OSX from disc" message. What can I do?

Did you erase the hard drive using the disc that you're trying to install from? Restart using that disc go back into Disk Utility and select the partition tab, select one partition and make sure that GUID partition scheme is checked, apply and then rename and format the disc as Mac OS extended Journaled. Your SL should install then.

When you erased he HD were you started from the install disc? Or from the Lion recovery partition? Start up with the install disc in and hold the C key down as soon as you hear the startup chime.

Insert your Snow Leopard disc and restart, press and hold the C key as soon as you hearthe startup chime, hold C until you see the Apple Logo. When your computer starts up you'll be at the first install screen, choose your language and click the arrow to go to the next screen. This screen has a menu bar, from the Utilities menu select Disk Utility, select your hard drive, this is the one with the manufacturers name or numbers, click the partition tab and then delete any existing partitions by selecting them and clicking the minus. In the drop down box select one partition and click apply. Name your hard drive and click erase. When it's done quit DU and go back to the installer, install Snow Leopard. When the installer is done and the computer is back up and running run Software Update to get to 10.6.8