I'm assuming you are saying that you don't have the foundational knowledge of how to control a device via MIDI commands, in which case I'd recommend starting with these as I have found them helpful, and seen others find the same. I've just gone through the same process recently setting up automation for some different devices and was learning ST3 at the same time. I do have a solid knowledge of MIDI and IT troubleshooting.
MIDI Programming & Commands Explained - How to Program MIDI
https://www.youtube.com/watch?v=IoUtshlzCTo&list=PLeo7dSvjxGd4UxzB4uYdNxjOuNC3rvkgg
How to Send & Receive MIDI with iPad APP - Stage Traxx 3 - Part 3
https://www.youtube.com/watch?v=R5IIrmJWKJ8&list=PLeo7dSvjxGd4iUM3u25HsC8W-JPxHw4BS&index=3
For your specific Mooer P2 Prime device, annoyingly it doesn't appear to have any default definitions on what it wants to receive via MIDI for patch changes. It is all "put the app into Learn mode and send it something". While flexible, it's a confusing place for beginners to start from.
Refer to p36 of the device manual - https://www.mooeraudio.com/npublic/opdfjs/web/viewer.html?file=https%3A%2F%2Fomo-oss-file.thefastfile.com%2Fportal-saas%2Fnew2022113010221252588%2Fcms%2Ffile%2Fprime%20p2_manual_en(1).pdf
Once you have these foundational pieces understood, I think you'll find these pages in the ST3 docs relevant:
https://stagetraxx.com/user-guide/lyrics/#adding-midi-commands
https://stagetraxx.com/user-guide/midi/#send-midi
You will have a fair bit of trial and error ahead of you!
The other trap I'd say to keep an eye out on is knowing whether your CME WIDI Jack should be in Type A or Type B mode, as getting that wrong will stop MIDI message from even getting to your device.