I have a document word, I want to convert it to PDF File, is there any free
software to use it for this?

Yes, there are is some. This is the one I have used. It is adwa annoying
(?) adds pop up after each pdf created unless you purchase it.

http://www.pdf995.com/

I recommend it. But if you are using a double byte language system (mine is
Japanese) bear in mind that the output folder has to be in a path using only
ascii (not double byte) characters. Or at least in the version I used.

Tim