Hi Scott
The best way is to get a program that can edit PDF files, however if it is only a few that you need to do, then bring the file up on-screen and press the Print Screen (PrtSc) button on the keyboard, (It will not appear to do anything) you can then paste it into any photo editing software (Including Microsoft Paint which comes as standard with Windows) and edit it from there.
Be aware that unless your photo editing software supports saving to PDF you will need to save it as a JPEG.
Hope this helps

Bill