#include <stdin.h>
That produces an error for my gcc has no such file. Try changing <stdin.h> to <stdio.h> (which is the norm).
main()
The above line doesn't produce any errors for me, but I believe it should really be:
int main(void)
{ printf("Hello World\n"); }
I'm not familiar with the precise compiler you're using. I use gcc (MinGW) on Win32.
If that's what the tutorial really said to do, then it sounds like a pretty crappy tutorial to me. I don't have any quality-guaranteed web tutorials to recommend. Maybe http://computer.howstuffworks.com/c.htm
is a better place to start learning - or, better still, one of the quality C/C++ books such as Kernaghan's.
Hope this helps.
Cheers, Rob