ostman to test the API that generates real-time speech from text

Hi i was given these prompts by chat gpt and i dont know whereto access either of these things:

Set Up Postman:

Open Postman.
Set up a POST request with the following endpoint (hypothetical example):
vbnet
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POST https://api.heygen.com/text-to-speech
Add the Authorization header (bearer token) provided by HeyGen.
Set the Content-Type to application/json.
In the Body section, type the following