If you didn't change the browser settings, the downloaded patch should be in (C:) > Users > Your Computer Account > Downloads folder. Also, it should be in .zip format and you can extract the package using WinRAR or WinZIP. If it isn't there, open your browser, go to Options and check where is the Downloads directory. If you still can't find the patch, change the Downloads directory to your desktop, use Google search engine to find the Map Builder and download it again. Once you download the utility, extract the patch using WinRAR or WinZip and launch it.