Your problem is that you copied this code from somewhere and hence, instead of using the ASCII double quotes (") you used some fancy quote marks (e.g. from MS Word), which means nothing to the compiler. You really have to use the ASCII double quotes.
Please, see the fixed code below:
#include <stdio.h>
int main()
{
int a,b,c;
printf("Ingrese el primer numero:");
scanf("%d",&a);
printf("Ingrese el segundo numero:");
scanf("%d",&b);
c=a+b;
printf("a + b = %d\n", c);
return 0;
}