How to use httpGet and httpPost for API

I want to make a connection to a device that requires an API connection. I was informed that in order to connect to Ignition I would need to make a custom API with the httpPost and httpGet methods. The end goal is to chart the temperature from the device in Ignition. Can someone give me some more guidance on how to do that specifically? I have the instructions from the support team on how to create the API and just need to know how to integrate it with Igniton. See link:

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