Count Date: Just simply set the date that you want to count down to (Note: It's American date, so it's mm/dd/yyyy)
Count Time: [24hr clock] Set the time that you want to count down to (example: 14:50:00 would be 2:50pm)
Refresh Rate: Set this to "1" if you want it to update for every minute, or leave it how it is.
Personal Message: Leave it how it is if you don't want to get confused, otherwise you can change it. The text below it explains what each of them mean.
Count Down End: This is what it will say once the countdown is at 0 hours 0 minutes and 0 seconds.
You might want to read
this thread.