The NowPDF Writer software installs a 'virtual printer' in windows.  You can verify this after installation is complete (and you restart your computer) by selecting 'Printers and Faxes' from the 'Start' Menu.  You should see a printer titled 'NowPDF Writer'

To start creating PDF files, open the document you would like to convert in whatever program it was created in.  (ie: Word, PowerPoint, Publisher, etc...)

From the 'file' menu select 'Print' and the print dialogue box will open (it may not look exactly like the screen shot below - it varies a bit from one program to another but the general idea is the same).

From the print dialogue window, select the printer 'NowPDF Writer' and click the 'Print' button.

NOTE:  Do NOT check the 'Print to file' options

Depending on your 'Preferences settings' you may be prompted to name your PDF file and select a location to save the file as shown below:

If you have 'View PDF after saving' selected under 'Preferences settings' the your new PDF file will open in Acrobat Reader automatically at this point.

NOTE:  Some large files containing high resolution graphics and photos may take a while to process the post script file just like it would if you were printing to your laser or inkjet printer.  It may seem like nothing happened but give it a minute and it will get there.