Welcome to the forum.
Here is a quick example :
#include <stdio.h>
extern int __stdcall testproc(int x, int y);
int main(int argc,char *argv[])
{
int x=125,y=75;
printf("125 + 75 = %d",testproc(x,y));
return 0;
}
.386
.model flat,stdcall
option casemap:none
.code
testproc PROC x:DWORD,y:DWORD
mov eax,x
add eax,y
ret
testproc ENDP