If you are using a word processor you may be able to simply "save as PDF" when you save the file. If you don't see "save as," you might also want to try selecting "Print," then in the options of sending to a printer or other form of software, it may also let you choose "Print to Adobe PDF" or another software that has a PDF printer (in looking at my printer choices I see Quicken also has one).

If you don't have this functionality in your word processor you may need to download a PDF maker. I haven't used Adobe Reader for a long time, but I'd start with Adobe and see if having that in your system allows you to save as PDF. (I can't test Reader for you because I have the full Adobe Acrobat software, and if I load Reader, it messes up my settings.)