How do I send an HTTP post request with headers and json data through a proxy with WinHTTP (C++)

I am attempting to send a post request like the one described in the title, but I cannot seem to find a good example of a generic piece of code. My work on my project is a bit tedious as I have never used WinHTTP, only libcurl before which is why I decided to ask here. To reiterate, the http request is a post request with specific header values and json data in the request body which is sent through a proxy to a website using winHTTP. If anyone could provide me with assistance, it would be greatly appreciated.