I need a 1-2 hour meeting/tutorial by desktop share with an expert to explain connecting my website to Letterstream using their API, and using http POST.
I have done some development but not in this language. I need an expert to answer my questions and help me get started to set up the basics of this API.
I will have a need for later support also, but to start I just need 1-2 hours tutorial around this http POST to connect the API.
I attached a screenshot of the stage I am at in Postman getting an error authenticating.