GoHighLevel - N00B Question

I am brand new to Make. Looking to make a switch from Zapier.
I am attempting to update/create a contact in GoHighLevel.

Data comes in from Google Sheets (its working)
BUT I CANNOT FIGURE OUT HOW TO SET UP THE QUERY IN THE GHL CONNECTION

And I cant find any documentation on this.

I see the data in the “rowValues” but no idea what to do next.

I want to:
a) find existing GHL contact and update or;
b) if not existing, create a new GHL contact

Can anyone share a screenshot or two to help get me started?