You can upgrade Internet Explorer in two ways. First one is to go to Internet Explorer interface and click "Tools", where you will find "Windows Update". Click on that feature, and a page with all updates available for your PC will open. The second option is to click the "Start" button, open "All Programs" and select from the list "Windows Update" that will open the same page where you find the upgrades available for you computer. Depending on your Windows version, instead of "Windows Update" you can find "Microsoft Update". Keep in mind that, in order for Internet Explorer 9 to properly work on your computer, Windows 7 is required.