Two ways to convert a picture file (PNG or GIF) into a PDF.
Method 1 - Print to PDF
Step #1: Click on the print icon.
Step #2: Select "Print to PDF" in your printer drop-down box.
Step #3: Make sure to save your document on your desktop or in a folder you can access easily.
Method 2 - Import your image into a Microsoft Word document.
Step #1: Click on File > Save as
Step #2: In the "Save as type" dropdown, select PDF. Also, select the location of your file, and rename it if necessary.
Another option you might consider is to download an App to your phone to use as a PDF scanner