Using a function from external .dll and .lib (EOS sdk)

Hi, I am trying to implement the Epic Online Services to my ue 4.24 project. I started a blank project, created the third party template plugin and loaded dll, lib and included the headers downloaded from sdk. But I dont know how to use the functions that dll or lib contains. I did search for this online and looked up to pretty much any topic related to this subject. But I cannot figure out how to call a function from loaded dll. I also created the BlueprintFunctionLibrary in c++ and included my sdk header, but what comes after that?

Can someone show me an example of using 1 function from this library or any external dll or library? I dont really understand the workflow here.