Here’s a video I stumbled across. It focuses on granular looping, but it does show some of the basics in the beginning:
https://youtu.be/cCxEJk2ztWg
The online documentation is very thorough, but skip to the end to see the Performance Parameters:
https://cdn.eventideaudio.com/manuals/h90/1.5.2/content/algorithms/looper.html
As for how to set those up, refer to the section on that, also in the manual:
https://cdn.eventideaudio.com/manuals/h90/1.5.2/content/play-modes/perform.html#performance-parameters
There is quite a bit of information on this forum about the H9 / TimeFactor Looper. The H90 Looper is an extended version of those others, but the same principles will apply.