Computer help please:- Saving documents as pdf files?

I have some work to type, and have to save the documents as .doc, .rtf and .pdf files.
I have many equations, figures and structures (chemsketch) to save also.
I can save the .doc files and .rtf files, but I don’t know how to save the .pdf files. The fonts have to be embedded.
I really don’t know how I would do this. Do I have to purchase software?
Any help would be appreciated.