Updating MacBook to El Capitan

I have a 2009 white unibody MacBook, with Intel Core 2 Duo,Processor Speed:2.26 GHz ,Processors:1 Total Number Of Cores:2, L2 Cache:3 MB Memory:2GB. It has OS X 10.6.8 with Safari 5.1.10 Snow Leopard. I have tried to update the OS X system to El Capitan after checking Apple's support site which stated that I could. After several attempts it would not install. I gave up and tried to re-install my original OS X Snow Leopard. It would not re-install. After using "Utilities" I copied the disc and eventually had "installation successful" - "restart". When I went to restart, I simply got the Apple white screen, with the rotating circle. Nothing further happens. I also cannot retrieve the installation disc from the machine either. I now just want to restore it to as much of the original OS X as possible so that I can upgrade memory or sell it. Can anyone help please? Thank You