Hi Mazen,
The file containing the TimeZones list is called TimeZones.xml and is stored inside the <RootDir>\App_GlobalResources folder.
If you have another locale different from en-US, then the file should be called TimeZones.[locale].xml, for example, for Mexico, it would be TimeZones.es-MX.xml.
Please note that the corresponding locale should be enabled and a proper Language Pack should have been installed in order to use that TimeZones file.
Saludos,
Alejandro.