It sounds like you are using the extractor instead of WinZip (www.winzip.com) proper.
When you open WinZip 7.0, you will get a window like this:
From there you:
1) open a new archive file by clicking on "New",
2) name your archive (not your PDF file). Example: test
WinZip automatically adds "zip" to your archive filename. If you put the "zip" in first, your archive name ends up as a confusing "test.zip.zip".
3) select your PDF file to include in the new archive by finding it though the window that opens and double-clicking the file. Example: hilton.pdf
4) click "Add". This closes the window.
5) The WinZip window then appears with your PDF file "hilton.pdf" listed.
The file you use to email or place on your website is this archive "test.zip".
Hope this helps.