The CommunicationClient_Test Exmple Add-On shows a simple example for using REST API, but the example can work for any other REST APIs with minimal modifications.
It's not required to use the SetId function. That depends on the server side implementation. That could be for example a session identifier or an identifier of various REST API methods. So if the used service does not require any id, then simply don't care about requestMethodId 😉
I see that you will have to pass parameters also. Use the AddParameter function of the request to define the parameters.