I struck in use thingworx GetJSON and convert it to infotable.

I followed this 2 topics
-How to convert JSON to an InfoTable in ThingWorx
https://www.ptc.com/en/support/article?n=CS179012
-About Convert JSON file to Infotable
https://community.ptc.com/t5/ThingWorx-Developers/About-Convert-JSON-file-to-Infotable/td-p/508236

I do
-I read the how to about make service to GetJSON from snippet.
-I try to create Datashape like JSON format i need to call.

I don't know
- Where to make GetJSON service execute? Does I have to create the thing first to use service?
- how to test result?

I think I need start to finish guideline about this
Can anyone show me this how to

Thankyou