forum said i should be able to upgrade to el capitan but system wont allow, wont let me upgrade to yosemite. Im new to mac(used windows forever) and am running into brick walls to get anything done. this os is apparently obsolete
See http://support.apple.com/kb/HT206886 - that lists what models will run El Capitan. If yours will, in that document find the "If your Mac doesn't support Sierra, or you're using Snow Leopard and would like to upgrade to Sierra, you can get El Capitan from the App Store" link.
If your Mac won't run El Capitan, it also would not run Yosemite, Mavericks, or Mountain Lion (all have the same system requirements). It might run OS X Lion.