How can we call the OAuth API's created for a product from Postman or Insomnia?

[BharadwajKura]

Hi SAP Gurus, 

I've created a OAuth API on API management and assigned it to a Product. Once I published the product, I'm able to see the Secret and Application Key. 

Now, can anyone advise how can I make the call to this API from Postman or Insomnia?

Regards/-
Bharadwaj Kura