How do I create Apple Partition Map?

Your Mac does not use APM, it uses GUID. Here's what you need to do. You will need the two DVDs that came with your computer when it was new. Please check this to determine if your model's firmware can be upgraded to use Internet Recovery: Computers that can be upgraded to use OS X Internet Recovery.

Snow Leopard Erase and Install

If possible be sure to back up your files.

1. Insert Snow Leopard DVD into the optical drive and restart the computer.
2. Immediately upon hearing the chime hold down the C key.
3. Release the key when the Apple logo appears and wait for the loading to finish.
4. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities' menu. After Disk Utility loads select the out-dented disk entry from the side list (mfgr.'s ID and drive size.) Click on the Partition tab in the Disk Utility’s right window. Set the number of partitions to one (1) from the drop down menu. Click on the Options button and select GUID, click OK button, set the format type to MacOS Extended, Journaled. Finally, click on the Apply button.
5. After formatting has finished quit Disk Utility. Continue with the OS X installation and follow the directions.
6. When the installation has finished the computer will restart into the Setup Assistant. After you complete the Setup Assistant you will be running a fresh installation of Snow Leopard. Open Software Update and install the recommended updates.
7. Download and install Mac OS X 10.6.8 Update Combo v1.1. You can upgrade from here via the App Store.