It shouldn't be as difficult as it seems to be for you.
Please explain, step by step, what you have done so far (BTW, why aren't you using the CD that came with the printer rather than downloading the driver?).
What browser did you use to download the file -- Internet Explorer, Firefox, Chrome, Opera, something else? What version (this is generally shown in the Help menu (About ...), although if you have IE 9, you need to click the gear icon in the upper right corner (next to the house and star icons).
Where did you look for the file that you downloaded? If you are using IE 9, click on the gear icon I described above and click on "View Downloads."
The file you should have downloaded is named
PP1350W_win7_x64_v1.0.0.0_Eng.zip
If you really have no idea where the download was saved (normally, it is in your Downloads folder), just click My Computer and copy and paste that file name into the search box at the upper right corner.
You should also download the "Release Notes" document whose link is just above the link for the driver download. The Release Notes requires Adobe Reader in order to read it. You probably have that already, but if not -->http://get.adobe.com/reader/ (IMPORTANT: UNCHECK the box to install McAfee Security Scan BEFORE you click the download button).
Once you find that file, you'll have to right-click on it and select "Extract all." After the files have been extracted, go to the folder into which you extracted the files, keep clicking on the folders until you get to the one with the files. Then double click on setup.exe. Leave the printer disconnected from the computer until the software either prompts you to connect it or finishes the installation.