You can download and install the Preview app, which is pre-installed on any Mac. You can add text, highlight, sign the papers, delete the pages, and even insert images. If you're wondering how to edit a PDF on Mac, Preview is the most beginner-friendly option. There is nothing more you can download; just open your PDF with Preview and start editing. More serious functions are available in other apps, too, such as Adobe Acrobat or PDF Expert, but the majority of users will be satisfied with the settings on Preview.