The process for connecting the Guppy to TG via TTN is the same as per the Oyster, aside from the destination URL.
See here: Oyster - Connecting to Telematics Guru over The Things Network
Configure your application, routing profile and device to have names relevant to the Guppy.
When setting up the HTTP integration (Step 6 of the Oyster Guide) use the URL specific to your region:
Refer to this article for an explanation of the regions.