Can't figure out how to use the compiler

[Plorf via Digitalmars-d]

I downloaded the DMD Windows compiler, installed it in the 
default directory, added its location to the system path, 
restarted my computer and wrote a sample "hello, world" program, 
and it won't compile; instead it says "Error: cannot read file 
hello.d". My computer is 64-bit, if that matters at all. Can 
someone please explain how to get the DMD compiler to work or 
provide some links? This has really been frustrating me. Thanks.