Adobe Acrobat is the most common way to make PDF files. You can convert one or a few files to pdf on adobe.com for free
Great alternative to Adobe
With the doc open in Word, go File menu > Print and then, if you have Adobe Acrobat PDFwriter loaded as one of your "printer" choices, you can "print" the file (even though, confusingly, nothing gets printed) and convert it to a PDF.
ONLINE FREE WORD TO PDF CONVERSION
The following are offering free services to convert word files into pdf's online: