Send Post using curl.h and SSL certificate in C - c

Question

I am trying to send a POST type message with HTTPS communication using the curl.h library but I have some doubts:
It is necessary to have the certificate in a file (possibly inside the project folder) or it can be taken dynamically (as PostMan does for example).
How should the format of the sending of data be.
How to receive the data is equal to an HTTP?
This is my program:
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <curl/curl.h>
BYTE str[20];
struct string
{
char *ptr;
size_t len;
};
void init_string(struct string *s)
{
s -> len = 0;
s -> ptr = malloc(s -> len + 1);
if (s -> ptr == NULL)
{
fprintf(stderr, "malloc() failed\n");
exit(EXIT_FAILURE);
}
s -> ptr[0] = '\0';
}
size_t writefunc(void *ptr, size_t size, size_t nmemb, struct string *s)
{
size_t new_len = s -> len + size * nmemb;
s -> ptr = realloc(s -> ptr, new_len + 1);
if (s -> ptr == NULL)
{
fprintf(stderr, "realloc() failed\n");
exit(EXIT_FAILURE);
}
memcpy(s -> ptr + s -> len, ptr, size * nmemb);
s -> ptr[new_len] = '\0';
s -> len = new_len;
return size * nmemb;
}
int post_function()
{
CURL *post;
CURLcode ret;
struct string s;
init_string(&s);
curl_global_init(CURL_GLOBAL_DEFAULT);
post = curl_easy_init();
curl_easy_setopt(post, CURLOPT_CUSTOMREQUEST, "POST");
curl_easy_setopt(post, CURLOPT_URL, "https://example.com/post.php");
curl_easy_setopt(post, CURLOPT_WRITEFUNCTION, writefunc);
curl_easy_setopt(post, CURLOPT_WRITEDATA, &s);
curl_easy_setopt(post, CURLOPT_SSL_VERIFYPEER, 0L);
curl_easy_setopt(post, CURLOPT_SSL_VERIFYHOST, 0L);
curl_easy_setopt(post, CURLOPT_POSTFIELDS, "------WebKitFormBoundary7MA4YWxkTrZu0gW\r\nContent-Disposition: form-data; name=\"data\"\r\n\r\nName\r\n------WebKitFormBoundary7MA4YWxkTrZu0gW--");
ret = curl_easy_perform(post);
if(ret == CURLE_OK)
{
sprintf(str, "Msj: %s\n", s.ptr);
}
else
{
//ERROR
}
curl_easy_cleanup(post);
curl_global_cleanup();
}
int main(int argc, char const *argv[])
{
post_function();
return 0;
}