I am very new to this, so apologies for the dumb question.
I cannot figure out how to do GET requests using PostMan. My issue is that I have an API KEY and a Secret KEY - I do not understand where I should put the Secret KEY.
The Secret KEY seems to be a second API Key. Thank you.
Welcome to the community 
The API key should probably be declared under the header section of the app. You can try to hit “Send” for this URL to get started: https://postman-echo.com/get. (Screenshot for reference)
Also, the most efficient way to start using Postman is with the help of in-app learning resource the “Bootcamp”. It provides you step by step way to use it. Also, our learning center encompasses a detailed explanation of every option within the app- feel free to leverage the search option to retrieve most of the details from it.
Will also be listing additional resources below for your reference:
Hope this helps! 
