NEED HELP pls Mac Pro (mid 2012) running high sierra 10.13.6

NEED HELP pls Mac Pro (mid 2012) running <a class='btn-link text-danger' href='/search/label/distro?max-results=12'>high sierra</a> 10.13.6

Completely NO CLUE how the installation process works. How would I go about installing the latest version of Mac OS without mainly compromising Adobe Illustrator, Photoshop, Premier pro ? Do I need to buy a new graphics card before starting the installation process?

Author: @Ilikedat888