SetTimer How do i use it?

Ok im using this code off of msdn

Code:

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SetTimer(hwnd,IDT_TIMER1,5000,NULL);

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i have it in the wm_create thing

is it suposed to be there because it is not working

i used

Code:

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#define IDT_TIMER1

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how do i make this work? Im a newbie sort of. I can make a
application window and buttons and common control so this is
new to me . I know alot about the other api's. But this one isnt
helping me. Can someone please help. Thanx

#define IDT_TIMER1 1
or (better, but C++ only)
const UINT_PTR IDT_TIMER1 = 1;