You use GetPrivateProfileString, just like you would in any other language.
C++ Code:
#include <windows.h>
#include <iostream>
int main()
{
// make sure that your buffer is large enough to hold
// all the characters... the return value of GetPrivateProfileString
// is the number of characters read.
// the number '32' below is supposed to be in brackets, but the
// forum highlighting breaks it.
char buffer[32];
GetPrivateProfileString("section", "key", "default value", buffer, sizeof(buffer), "myFile.ini");
std::cout << "the value key=" << buffer << std::endl;
return 0;
}