Get more information about your computer. Go to the Apple in the upper left corner of any window, then "About This Mac", then "More Info..." Copy and paste the information here, but omit the serial number and Hardware UUID (if present).
Exact web site URLs? You really are not giving us enough information to help you. We need to know exactly which site so we can determine what plugins are required to view it, then to know if your computer has those plugins, and if it doesn't, to then know if your computer is even capable of running the plugins, and in which browser.