We've had a few questions about PDFs...
Do you need to submit your document as a PDF for class or a conference?
Simply "Save as" and select "PDF" - this will allow you to save your files in a way that allow them to be easily viewed by others who perhaps don't have the same software.
*PDF stands for Portable Document Format
You can also use Adobe Reader (Free!) to fill and sign most PDF forms. Use the tool bar at the top to add a Text Box that will allow you to add content to a PDF form.
Use the "Sign" option to upload a copy of your signature and then you can add it to documents and forms.
TIP: you can sign your name on plain paper and take a photo with your phone to get a good signature image (I'm not using my real signature on this page incase anyone screen grabbed it for nefarious purposes....)