Mary,
I agree with Matt that it is infinitely better to have an algorithm beforehand. As I see it, you need to use the for loop as part of your exercise. So your psuedocode would be something like this.
int celsius;
for(celsius=42;celsius>31;celsius--)
{
double result= celsiusToFaren(celsius);
display(result)
}
Obviously, you will need to write the definitions of the
methods for "celciusToFaren" and "display".
Hope this helps
Ambi